FOR TRAINING USE ONLY
AW189
Pilot
Type Rating Ground Course (TRGC)
71 - Power Plant
Student Notes
DOCUMENT NO: AW189-TR001-SN-I-71
ISSUE: 8.0
ISSUE DATE: 18/10/2016
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
INTENTIONALLY
LEFT
BLANK
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
Table of Contents
Power Plant Lesson ............................................................................................................................................1
1 Purpose of the Power Plant System ........................................................................................................1
1.1
General Overview ...........................................................................................................................1
1.1.1 Introduction .................................................................................................................................1
1.2
General Layout of the Power Plant.................................................................................................3
1.2.1 Engines Layout ...........................................................................................................................3
1.2.2 Services ......................................................................................................................................4
1.3
Engine Bays ....................................................................................................................................5
1.3.1 Description ..................................................................................................................................5
1.3.2 Lightning Protection Unit (LPU) ..................................................................................................6
1.4
Engine Intakes ................................................................................................................................7
1.4.1 Description ..................................................................................................................................7
1.5
Engine Mountings ...........................................................................................................................8
1.5.1 Rear Mountings ..........................................................................................................................8
1.6
Airframe Provisioned Drains ...........................................................................................................9
1.6.1 Description ..................................................................................................................................9
2 Power Plant Engine Control ..................................................................................................................10
2.1
General Overview .........................................................................................................................10
2.1.1 Introduction ...............................................................................................................................10
3 Engine Module Introduction ...................................................................................................................11
3.1
Engine System Purpose ...............................................................................................................11
3.1.1 Engine Characteristics ..............................................................................................................11
3.1.2 Power Ratings ..........................................................................................................................12
3.1.3 Engine Peculiarities ..................................................................................................................13
3.2
Engine General Architecture ........................................................................................................14
3.2.1 Introduction ...............................................................................................................................14
3.2.2 Main Bearings ...........................................................................................................................15
3.3
Basic Engine Architecture ............................................................................................................17
3.3.1 Description ................................................................................................................................17
4 Engine Module Control ..........................................................................................................................18
4.1
Engine Control Components ........................................................................................................18
4.1.1 Electronic Engine Control Unit ..................................................................................................18
4.2
Engine System Control Purpose ..................................................................................................19
4.2.1 Introduction ...............................................................................................................................19
5 Engine Fuel and Control Module ...........................................................................................................20
5.1
Engine Fuel System Purpose .......................................................................................................20
5.1.1 Introduction ...............................................................................................................................20
5.2
Engine Fuel System Architecture .................................................................................................21
5.2.1 Description ................................................................................................................................21
6 Engine Fuel and Control System Components .....................................................................................22
6.1
Description ....................................................................................................................................22
6.1.1 Engine Boost Pump and Pressure Switch ................................................................................22
6.1.2 Fuel Filter and Bypass ..............................................................................................................23
6.1.3 Fuel Metering Unit ....................................................................................................................24
6.1.4 Fuel Manifold ............................................................................................................................25
6.1.5 Fuel Injectors ............................................................................................................................26
6.1.6 External Fuel Pipes ..................................................................................................................27
7 Engine Fuel and Control System Operation ..........................................................................................28
7.1
Operation of the Engine Fuel Control System ..............................................................................28
7.1.1 Engine Fuel System Operation.................................................................................................28
8 Engine Electric and Ignition Module ......................................................................................................30
8.1
Ignition System Purpose ...............................................................................................................30
8.1.1 Introduction ...............................................................................................................................30
8.2
Ignition System Architecture .........................................................................................................31
Issue No 8.0
18/10/2016
Page i
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
8.2.1 Description ............................................................................................................................... 31
8.3
Ignition System Components ....................................................................................................... 32
8.3.1 Igniter Plug ............................................................................................................................... 32
8.3.2 Permanent Magnet Alternator .................................................................................................. 33
9 Engine Air Module ................................................................................................................................. 34
9.1
Engine Air System Purpose ......................................................................................................... 34
9.1.1 Introduction .............................................................................................................................. 34
9.2
Engine Air System Architecture ................................................................................................... 35
9.2.1 Description ............................................................................................................................... 35
10
Air Module Components .................................................................................................................... 37
10.1
Engine Air System Components .................................................................................................. 37
10.1.1
Inlet Particle Separator ...................................................................................................... 37
10.1.2
Inlet Particle Separator Blower .......................................................................................... 38
10.1.3
Variable Geometry System ............................................................................................... 39
10.1.4
Anti-icing and Start Bleed Valve ........................................................................................ 40
10.1.5
Cooling Pipes .................................................................................................................... 41
10.1.6
Air System Sensor (T2) ..................................................................................................... 42
10.1.7
Air System Sensors (P3) ................................................................................................... 43
10.1.8
Air System Sensors (P0) ................................................................................................... 44
11
Air Module Operation ........................................................................................................................ 45
11.1
Operation of the Engine Air System ............................................................................................ 45
11.1.1
Operation ........................................................................................................................... 45
11.1.2
Monitoring .......................................................................................................................... 47
12
Engine Control Module ...................................................................................................................... 48
12.1
General Overview ........................................................................................................................ 48
12.1.1
Engine Control Introduction ............................................................................................... 48
12.1.2
FADEC Introduction .......................................................................................................... 49
12.2
Engine Control System Architecture ............................................................................................ 50
12.2.1
Engine to Cockpit Interfaces ............................................................................................. 50
12.2.2
Engine Control Architecture .............................................................................................. 51
12.3
Engine Control System ................................................................................................................ 52
12.3.1
Engine Control Panel ........................................................................................................ 52
12.3.2
Miscellaneous Control Panel ............................................................................................. 53
12.3.3
Engine Power Collective Anticipator LVDT ....................................................................... 54
12.3.4
AEO and OEI Limit Switches............................................................................................. 55
12.3.5
Electronic Engine Control Unit .......................................................................................... 56
13
Engine Control Components ............................................................................................................. 57
13.1
Engine Electrical System Components........................................................................................ 57
13.1.1
Engine Np (Nf) Sensor ...................................................................................................... 57
13.1.2
Thermocouple Harness ..................................................................................................... 58
13.1.3
Permanent Magnet Alternator ........................................................................................... 59
14
Engine Control Operation .................................................................................................................. 60
14.1
General Overview ........................................................................................................................ 60
14.1.1
Introduction ........................................................................................................................ 60
14.1.2
Engine Power Ratings ....................................................................................................... 61
14.1.3
Overspeed/Shutdown System ........................................................................................... 62
14.1.4
Training Mode ................................................................................................................... 63
14.1.5
EECU Fault Management ................................................................................................. 65
15
Engine Indicating Module .................................................................................................................. 66
15.1
Purpose of the Engine Indications ............................................................................................... 66
15.1.1
Engine Indications Introduction ......................................................................................... 66
15.2
Engine Indicating Architecture ..................................................................................................... 67
15.2.1
Description......................................................................................................................... 67
16
Controls and Indications .................................................................................................................... 68
16.1
Description ................................................................................................................................... 68
16.1.1
Engine Display .................................................................................................................. 68
Issue No 8.0
18/10/2016
Page ii
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.2
Power Index .......................................................................................................................69
16.1.3
Power Index Indicator (PI%) ..............................................................................................70
16.1.4
Rating Legend ....................................................................................................................71
16.1.5
Rotor Droop Threshold.......................................................................................................72
16.1.6
OEI Training Mode .............................................................................................................73
16.1.7
Typical Engine Scales ........................................................................................................74
16.1.8
Engine Synoptic Format .....................................................................................................76
16.1.9
MFD Engine Primary Parameters ......................................................................................77
16.2
Engine Indications Warnings and Cautions ..................................................................................78
16.2.1
Engine Warnings ................................................................................................................78
16.2.2
Engine Cautions .................................................................................................................79
16.2.3
Engine Cautions Continued ...............................................................................................80
16.2.4
Engine Advisories ..............................................................................................................81
17
Engine Exhaust Module .....................................................................................................................82
17.1
General Overview .........................................................................................................................82
17.1.1
Introduction ........................................................................................................................82
17.2
Engine Exhaust Components .......................................................................................................83
17.2.1
Exhaust Nozzle ..................................................................................................................83
17.2.2
Exhaust Ejector ..................................................................................................................84
18
Engine Oil Module ..............................................................................................................................85
18.1
Engine Oil System Purpose ..........................................................................................................85
18.1.1
Lubrication System Introduction .........................................................................................85
18.2
Oil System Architecture ................................................................................................................86
18.2.1
Description .........................................................................................................................86
19
Engine Oil System Components ........................................................................................................87
19.1
Description ....................................................................................................................................87
19.1.1
Oil Tank ..............................................................................................................................87
19.1.2
Lubrication and Scavenge Pump .......................................................................................88
19.1.3
Oil Filter ..............................................................................................................................89
19.1.4
Oil System Sensors ............................................................................................................90
19.1.5
Chip Detector .....................................................................................................................91
19.1.6
Oil Cooler ...........................................................................................................................92
20
Engine Oil System Operation .............................................................................................................93
20.1
Description ....................................................................................................................................93
20.1.1
Oil System Operation .........................................................................................................93
20.1.2
Emergency Oil System Operation ......................................................................................95
21
Engine Starting...................................................................................................................................96
21.1
Engine Starting System Architecture ............................................................................................96
21.1.1
Description .........................................................................................................................96
22
Engine Starting Components .............................................................................................................98
22.1
Description ....................................................................................................................................98
22.1.1
Starter Generator - Location ..............................................................................................98
23
Engine Starting Controls and Indications ...........................................................................................99
23.1
Description ....................................................................................................................................99
23.1.1
Engine Control Panel .........................................................................................................99
23.2
Engine Starting Indications .........................................................................................................100
23.2.1
MFD/P-PLANT Page ........................................................................................................100
24
Engine Starting Operation ................................................................................................................101
24.1
Description ..................................................................................................................................101
24.1.1
Engine Starting - Normal ..................................................................................................101
24.1.2
Engine - Crank .................................................................................................................103
24.1.3
Hot Start Prevention .........................................................................................................104
24.1.4
Hot Start Prevention .........................................................................................................104
24.1.5
Aborted Start Procedures.................................................................................................105
24.1.6
Restarting Engines ...........................................................................................................105
24.1.7
Restarting Engines ...........................................................................................................106
Issue No 8.0
18/10/2016
Page iii
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
INTENTIONALLY
LEFT
BLANK
Issue No 8.0
18/10/2016
Page iv
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
Power Plant Lesson
1
Purpose of the Power Plant System
1.1
General Overview
1.1.1
Introduction
The AW189 helicopter has two General Electric CT7-2E1 turboshaft engines which drive both
the main rotor and the anti-torque rotor, through the aircraft transmission system. The purpose
of the power plant system is to integrate the engines into the aircraft. There are two aspects to
this function:

Engine installation

Engine control and monitoring (covered in a later module).
Engine installation comprehends all the mechanical components necessary to integrate the
engine into the aircraft structure. This includes:

Engine mounts

Intakes and exhausts

Engine driveshafts

Engine services (for example fuel and air supplies, drains).
Engine control and monitoring comprises all the components necessary to control the engine
and to monitor its outputs. This includes:
Issue No 8.0
18/10/2016
Page 1
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot

Engine controls in the cockpit

Inputs from the aircraft's flight controls

Electronic Engine Control Unit (EECU)

Cockpit Display System (CDS) functions

Aircraft Management & Mission System (AMMS) functions.
The above systems will be covered in more detail in later modules.
Issue No 8.0
18/10/2016
Page 2
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.2
General Layout of the Power Plant
1.2.1
Engines Layout
The two engines are installed above the aircraft cabin roof.
No. 1 engine is to the left, No. 2 is to the right side.
The Auxiliary Power Unit (APU) is located in between.
The two main engines and the APU are installed in bays, separated from each other and from
the aircraft structure by firewalls. Access is provided for the engine intakes and exhausts and for
engine services.
Issue No 8.0
18/10/2016
Page 3
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.2.2
Services
There are a number of services which are supplied by the airframe to the engine as part of the
power plant. These include:

Fuel supply

Electrical power

Engine control

Drains

Compressor wash.
The engines supply the following to the airframe:

Power drive to the transmission

Air (customer bleed).
Issue No 8.0
18/10/2016
Page 4
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.3
Engine Bays
1.3.1
Description
Each engine is in a bay which consists of a set of titanium firewalls and a metallic cowling with a
titanium inner protective skin. The APU bay firewalls are made of titanium and the complete
installation including joints, fittings and seals are all fireproof.
The edges of each engine bay floor are curved to allow fluid leaks and spillages to flow down
dedicated drains. This prevents leaked fluids from running down the fuselage sides.
The engine bay floors are equipped with a number of drains which are configured to prevent the
accumulation of fluids.
Issue No 8.0
18/10/2016
Page 5
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.3.2
Lightning Protection Unit (LPU)
As the airframe structure of the AW189 is partially composite, the threat levels of lightning
induced effects is increased. The Lightning Protection Unit (LPU) provides auxiliary transient
protection to ensure the FADEC components survive residual lightning effects.
The LPU is mounted on the inboard side of the inner firewall for each engine below the APU
floor, it allows the normal input and output signals required for engine control and aircraft
communication to pass through. All cables between the Electronic Engine Control Unit (EECU)
and the airframe are routed through the LPU.
Issue No 8.0
18/10/2016
Page 6
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.4
Engine Intakes
1.4.1
Description
The air is provided to each engine by means of a dedicated air inlet.
The forward inlet is a two-piece, vertically split composite structure which is installed around the
engine torque tube assembly. The forward inlet is installed forward of the front firewalls and
outside the engine bay fire zone.
The rear inlet ring comprises a vertically split, two-piece metallic fireproof ring. This mounts
directly to the engine and interfaces with a fireproof seal mounted on the front firewall.
Each inlet incorporates a drain at the bottom in order to prevent the accumulation of fluids.
Issue No 8.0
18/10/2016
Page 7
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.5
Engine Mountings
1.5.1
Rear Mountings
The rear engine mounting system provides support through a system of link assemblies which
interface with the engine casing via four dedicated lugs.
Issue No 8.0
18/10/2016
Page 8
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
1.6
Airframe Provisioned Drains
1.6.1
Description
The airframe provisioned engine drain pipes are taken from the engine bay and routed internally
through the aircraft structure to the underside of the aircraft where they assemble in a cluster.
Issue No 8.0
18/10/2016
Page 9
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
2
Power Plant Engine Control
2.1
General Overview
2.1.1
Introduction
The CT7-2E1 control system is a modern dual- channel Full Authority Digital Electronic Control
(FADEC) system. The FADEC system includes two major components, an EECU and a Fuel
Metering Unit (FMU). The EECU modulates fuel flow and schedules the compressor variable
geometry and start bleed-air. The following controllers are provided to protect engine and
aircraft limits:

Power turbine RPM (free power turbine speed (Nf or Np))

Load sharing :Torque (Tq) or Temperature (ITT)

Maximum and minimum gas generator RPM (Ng)

Maximum gas generator acceleration and deceleration

Maximum Interturbine Temperature (ITT)

Minimum fuel flow (to facilitate starting) and Maximum fuel flow

Maximum engine torque limiting.
Issue No 8.0
18/10/2016
Page 10
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3
Engine Module Introduction
3.1
Engine System Purpose
3.1.1
Engine Characteristics
Engine ratings at ISA sea level are as follows:
Rotational speeds:

Gas generator 44,700 rpm (100%)

Power turbine and output shaft 22,000 rpm (102%).
Issue No 8.0
18/10/2016
Page 11
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3.1.2
Power Ratings
The CT7-2E1 engine is capable of the following thermal performance when installed in the
AW189 aircraft under International Standard Atmosphere (ISA) sea level conditions.
Power Rating
Limit
Power Output
Max continuous
1870 SHP (1391 kW)
5 minute limit
1983 SHP (1476 kW)
OEI (One Engine Inoperative)
Max continuous
1983 SHP (1476 kW)
OEI contingency limit
2.0 minute limit
2104 SHP (1569 kW)
OEI contingency limit
30 second limit
2104 SHP (1569 KW)
Rating
AEO (All Engines Operating)
AEO take-off
Issue No 8.0
18/10/2016
Page 12
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3.1.3
Engine Peculiarities
The CT7 series of engines incorporate design features resulting from the experience gained
during operation in severe environment. The major peculiarities are:

Foreign Object Damage (FOD) and erosion damage caused by sand and dust ingestion. An
integral Inlet Particle Separator (IPS) is provided and the compressor section and other
engine components are of robust construction.

Engine oil loss due to damage and low maintenance. The oil tank and many oil pathways
are integrated with the engine casings and there is a high level of filtration.

Fuel leaks caused by damage or accidents. The engine has its own engine driven boost
pump which can draw fuel from the airframe fuel system. Fuel lines on the engine have
shrouded connectors to prevent leaked fuel getting onto hot surfaces.

Reduced pilot workload. A Full Authority Digital Engine Control (FADEC) system controls
engine operation and reports engine status to the aircraft systems, allowing the pilot
"carefree" handling.

Time consuming maintenance. The engine is modular and has a number of features which
make for ease of maintenance:
o
o
o
o
On condition maintenance philosophy
Minimum use of safety wire
Spring clamps and foolproof connectors for electrical harness
No adjustments after maintenance.
Issue No 8.0
18/10/2016
Page 13
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3.2
Engine General Architecture
3.2.1
Introduction
The CT7-2E1 is a turboshaft engine with gas generator and power turbine. The gas generator
consists of a five-stage axial compressor and a single-stage centrifugal compressor, coupled to
a two-stage gas generator turbine.
The power turbine is a two-stage axial type with a coaxial shaft which passes through the gas
generator to the front of the engine. At the front of the engine, the power turbine shaft drives the
output shaft assembly, which is connected to the MGB through a high-speed driveshaft.
Ambient air enters the engine through the Inlet Particle Separator (IPS), which is designed to
protect the engine from FOD and the ingestion of sand and dust. Air enters the IPS through the
swirl frame, vanes then direct the air into a rotating or swirling pattern to separate sand, dust
and other foreign objects by centrifugal action. These heavy particles are carried to the outer
section of the main frame, through a series of scroll vanes and into the scroll case. Suction
created by an engine driven blower removes the dirty air and expels it away from the engine via
aircraft ducting.
Air that remains after particle separation is carried to the front frame deswirl vanes, which
straighten and direct the airflow to the inlet of the compressor.
The combustion section of the engine consists of an annular combustion chamber with 12 fuel
nozzles and two igniter plugs. The temperature of the gas flow is measured by a ring of 7
thermocouples in the duct between the gas generator turbine and the power turbine. The air is
exhausted away from the aircraft by the exhaust nozzle assembly.
Issue No 8.0
18/10/2016
Page 14
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3.2.2
Main Bearings
The single-spool gas generator is supported by a ball bearing (No. 3) at the forward end and a
roller bearing (No. 4) in the centre.
The power turbine is supported by two bearings (No. 5 and No 6) at the rear and by the output
shaft assembly at the front.
The output shaft assembly is supported by a duplex ball bearing (No. 1) and by a roller bearing
(No. 2).
There are three sealed bearing chambers in the engine, which contain the bearing races.
Bearings No. 1, 2 and 3 are contained in a single chamber called the "A-sump", which forms
part of the engine intake section.
Bearing No. 4 is in the "B-sump", which is contained within the engine combustion section.
Bearings No. 5 and 6 are in the "C-sump", which forms the centre body of the engine exhaust
frame.
The ball bearings absorbs axial (thrust) and radial loads; roller bearings absorb radial loads
only.
All roller bearings contain spring cage roller supports which keep the bearings centred and
dampens vibration.
The engine manufacturer has designated a number of "stations" within the engine. These are
used to define engine operating parameters.
Issue No 8.0
18/10/2016
Page 15
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
The air pressure in the combustion chamber (station 3) is designated "P3" and the temperature
of the gases passing between the gas generator turbine and the power turbine (station 4.5) is
designated "ITT" (Interturbine Temperature).
Issue No 8.0
18/10/2016
Page 16
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
3.3
Basic Engine Architecture
3.3.1
Description
The CT7-2E1 engine consists of four modules:

Accessory section

Cold section

Hot section

Power turbine.
Issue No 8.0
18/10/2016
Page 17
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
4
Engine Module Control
4.1
Engine Control Components
4.1.1
Electronic Engine Control Unit
The primary component of the FADEC is the EECU, which is mounted on the bottom of the
engine.
The EECU consists of the following:

Two identical control channels which carry out the control computing functions:
o
o

Channel A - (blue cable)
Channel B - (green cable).
A power supply module which ensures continuous electrical power supplies to the two
control channels under all conditions.
The use of two identical control channels gives full redundancy for all the control functions.
The standby channel receives all data and does all the relevant calculations, but its control
outputs are inhibited. The choice of master control channel is fully automated.
Issue No 8.0
18/10/2016
Page 18
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
4.2
Engine System Control Purpose
4.2.1
Introduction
All engine functions are controlled and monitored by electrical signals which pass through
colour-coded cable harnesses between the various components.
The blue (channel A) and green (channel B) cable harnesses carry the duplex control and
feedback signals between the EECU/Fuel Metering Unit (FMU) and the engine systems and
speed, temperature, pressure sensors.
Issue No 8.0
18/10/2016
Page 19
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
5
Engine Fuel and Control Module
5.1
Engine Fuel System Purpose
5.1.1
Introduction
The engine fuel system operates with the engine electrical system to provide the proper fuel
flow during all operating conditions. In the CT7-2E1, the Electronic Engine Control Unit (EECU)
and the Fuel Metering Unit (FMU) have complete control of engine power.
The fuel system is designed to provide the proper fuel flow to the engine under all operating
conditions including starting, idle, acceleration, normal flight and maximum power. The
mechanical fuel system is itself an integral part of a Full Authority Digital Electronic Control
(FADEC) computerised system which controls the engine outputs to give constant power turbine
speed under any load conditions.
In addition, the engine philosophy requires that the risk of fire should be minimised in the event
of damage. Therefore, the engine fuel system has the following features:

Full suction feed capability provided by an engine driven boost pump

Fuel passages incorporated into the Accessory Gearbox (AGB) casing

Fuel pipe end connections shrouded and drained to remote locations.
Issue No 8.0
18/10/2016
Page 20
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
5.2
Engine Fuel System Architecture
5.2.1
Description
The engine fuel system components are connected to and driven by the AGB, mounted on the
top front section of the engine.
On the front face of the AGB are:

Engine Boost pump (Low Pressure)

Filter

Cooler

Pressure switch
On the rear face of the AGB is the FMU, this controls the correct flow of fuel to the engine under
all conditions of starting and flight under the control of the EECU.
To assist in the fuel control the FMU contains various components, these include:

High Pressure (HP) pump

Metering valve

Overspeed valve

Drain valve and vent

Variable geometry control.
Issue No 8.0
18/10/2016
Page 21
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6
Engine Fuel and Control System Components
6.1
Description
6.1.1
Engine Boost Pump and Pressure Switch
Engine Boost Pump (LP)
The engine boost pump is capable of providing suction to draw fuel from fuel tanks. This
decreases the fire hazard in case of a damaged fuel line.
The pump is mounted on the front face of the AGB and delivers fuel through a cored passage to
the fuel filter.
Fuel Pressure Switch
The fuel pressure switch is mounted on the left side of the front gearbox housing on the AGB.
The fuel pressure switch senses low fuel pressure.
Issue No 8.0
18/10/2016
Page 22
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6.1.2
Fuel Filter and Bypass
The fuel filter is a disposable type, high capacity filter with an impending bypass switch. It is
mounted on the forward left side of the engine AGB.
The fuel filter provides a 30-micron absolute filtration for engine fuel prior to entering the HP
pump in the FMU.
A fuel filter bypass switch sends an electrical signal if the differential pressure across the filter
rises to a preset value 1(2) FUEL FILTER. This value is lower than the differential
pressure necessary to open the filter's internal bypass valve.
Issue No 8.0
18/10/2016
Page 23
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6.1.3
Fuel Metering Unit
The FMU is mounted on the rear of the AGB and receives filtered fuel. The FMU contains a HP
fuel pump which pressurises the fuel for efficient burning. Other functions within the FMU
include:

Fuel metering - the correct amount of fuel is sent to the fuel manifold.

Variable geometry operation - feedback signal for control purposes to the EECU.

Engine shutdown - the FMU contains the overspeed valve which is used to stop the engine
when commanded by the pilot, or in the event of an overspeed being detected.

A metering valve position signal and a fuel temperature signal to allow computation of fuel
flow.
All these functions are controlled by the EECU, which supplies electrical command signals to
the FMU internal functions.
Within the FMU is an electronic sensor which supplies a dual electrical signal proportional to Ng
for each channel. Those signals are used as the primary Ng signal by the EECU channels.
Issue No 8.0
18/10/2016
Page 24
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6.1.4
Fuel Manifold
The fuel manifold consists of a double sealed tube and 12 fuel injectors mounted around the
diffuser and midframe casing assembly. The tube carries fuel from the overspeed valve in the
FMU to the injectors.
Issue No 8.0
18/10/2016
Page 25
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6.1.5
Fuel Injectors
Twelve fuel injectors, installed in the midframe, receive fuel from the fuel manifold and supply it
to the combustion liner swirlers.
Fuel from the injector is fed into the combustion liner and the mixed with the airflow which
breaks up the fuel flow into a fine atomised spray.
Issue No 8.0
18/10/2016
Page 26
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
6.1.6
External Fuel Pipes
The engine fuel system has a small number of fuel pipes which carry fuel to external
components. To reduce the chances of fuel leakage onto the hot surfaces of the engine, the
braided flexible sections are covered in a protective rubber tubing.
Issue No 8.0
18/10/2016
Page 27
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
7
Engine Fuel and Control System Operation
7.1
Operation of the Engine Fuel Control System
7.1.1
Engine Fuel System Operation
Fuel from the aircraft system enters the engine at the engine boost pump inlet. The engine
boost pump increases the fuel pressure and passes the fuel into passageways in the AGB.
The fuel filter collects impurities from the fuel. If the fuel filter becomes partially blocked, the fuel
filter bypass switch gives an indication of impending bypass before the filter's internal bypass
valve opens. Fuel from the filter enters the FMU where the HP fuel pump increases the pressure
still further to ensure efficient combustion. The pressurised fuel then passes through a metering
valve which controls the flow of fuel to the injectors.
Pressurised, metered fuel passes through the AGB to the oil cooler and then through the drain
valve in the overspeed valve to the fuel manifold and injectors.
Pressurised (but unmetered) fuel is also used as a servo to operate the variable geometry
system actuator. This servo fuel is returned to the main fuel flow at the HP pump inlet.
The overspeed valve shuts off the fuel supply during a normal engine shutdown or if an
overspeed is detected. If an overspeed occurs, the overspeed valve shuts off the fuel supply,
leaving the manifold full of fuel ready for automatic relight. Fuel pressure is recycled to the HP
pump inlet. When the overspeed valve operates during normal shutdown as fuel pressure
decreases, the drain valve opens and fuel in the manifold and injectors is blown back by air
pressure through the overspeed and drain valves into an overboard drain (wet drain). This is
known as "purging" and prevents the build-up of carbon in the injectors.
Issue No 8.0
18/10/2016
Page 28
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
The EECU provides electrical signals which control the operation of the engine and send engine
data to the aircraft systems.
Issue No 8.0
18/10/2016
Page 29
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
8
Engine Electric and Ignition Module
8.1
Ignition System Purpose
8.1.1
Introduction
The ignition system is a continuous duty, AC powered, capacitor discharge, low voltage system.
It includes two igniter plugs, two electrical ignition leads, and an ignition exciter assembly.
Power is supplied to the ignition exciter assembly by the Permanent Magnet Alternator (PMA)
as commanded by the Electronic Engine Control Unit (EECU).
Issue No 8.0
18/10/2016
Page 30
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
8.2
Ignition System Architecture
8.2.1
Description
Control of the ignition system is provided by channels A and B of the Electronic Engine Control
Unit (EECU), upon initial start the power for the EECU and therefore operation is from the
aircraft 28 Vdc supply, until such time as the engine has reached 24% Ng where there is
sufficient speed for the permanent magnet alternator (PMA) windings to provide power to the
EECU and engine alike.
Note: The igniter exciter receives power from the Permanent Magnet Alternator (PMA) only.
Issue No 8.0
18/10/2016
Page 31
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
8.3
Ignition System Components
8.3.1
Igniter Plug
An engine set consists of two igniters located one each at the 4 o'clock and 8 o'clock positions.
The plug is designed to create a spark across the electrode gap with the given voltage.
Issue No 8.0
18/10/2016
Page 32
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
8.3.2
Permanent Magnet Alternator
The gas generator driven Permanent Magnetic Alternator (PMA) is mounted on the front face of
the accessory gearbox. It has four windings within the rotor/stator assembly which supply AC
electrical power through the engine harnesses (Ng>59%).
For the purpose of the ignition system only one of the windings is used:

Winding No. 1 - igniter exciter assembly.
Once the engine has reached 24% Ng the PMA will provide enough power to the igniter exciter
for starting purposes, the control signals for ignition are sent from the EECU (Ng16%).
Issue No 8.0
18/10/2016
Page 33
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
9
Engine Air Module
9.1
Engine Air System Purpose
9.1.1
Introduction
The purpose of the air system is to provide:

Combustion

Cooling and pressurisation

Anti-icing

Customer bleed (air supply to aircraft systems).
Issue No 8.0
18/10/2016
Page 34
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
9.2
Engine Air System Architecture
9.2.1
Description
The architecture of the air system can be categorised into seven distinct stages.
Inlet Particle Separator (IPS)
Removes up to 85% of the dirty air and allows the clean air to enter as the primary airflow.
Five-stage Axial Flow Compressor
Compresses the air as it travels through the stages, the first two being part of the variable
geometry system which guides the air into the compressor at the correct angle for the next
stage of compression at varying engine speeds and conditions.
One-stage Centrifugal Compressor
Further compresses the air and guides it to the diffuser.
Annular Combustor
Mixes the compressed air with atomised fuel to rapidly heat and expand the airflow for the next
stage.
Two-stage Gas Generator Turbine
Draws some of the energy from the resulting airflow to drive the compressor therefore inducing
further airflow into the engine.
Two-stage Power Turbine
Draws a vast amount of the remaining energy from the airflow to drive the free power turbine
shaft which in turn drives the transmission system.
Issue No 8.0
18/10/2016
Page 35
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
Exhaust Nozzle
Provides a straightening affect to the remaining airflow to guide it into the exhaust ejector and
out to atmosphere.
Some of the air is used from various stages to feed secondary systems, control sensors and
components.
Issue No 8.0
18/10/2016
Page 36
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10
Air Module Components
10.1
Engine Air System Components
10.1.1
Inlet Particle Separator
Contaminated air enters the separator from the intake through to the swirl frame. Swirl vanes
direct the air into a rotating or swirling pattern to separate sand, dust and other foreign objects
by centrifugal action.
These particles are carried to the outer section of the main frame, through a series of scroll
vanes commonly called the nose splitter, and into the scroll case.
The particles are pulled from the scroll case by the blower and are blown out through an
airframe supplied overboard duct.
Air that remains after particle separation is carried to the front frame deswirl vanes, which
straighten and directs the airflow to the inlet of the compressor.
Issue No 8.0
18/10/2016
Page 37
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.2
Inlet Particle Separator Blower
The IPS blower is attached to the accessory gearbox by a series of mounting studs.
Whenever the accessory gearbox is turning, the dirty air and any particles are pulled from the
scroll case by the suction created from the blower.
Air then flows up through the inlet duct, past the impeller to guide it and through a set of
straightening vanes around the outside of the blower.
Dirty air then enters the blown air stream at the blower exit and is blown out through an airframe
supplied overboard duct.
Issue No 8.0
18/10/2016
Page 38
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.3
Variable Geometry System
The variable geometry system of the CT7-2E1 high performance compressor permits optimum
performance over a wide range of operating conditions. Use of Variable Stator Vane (VSV)
angles ensures rapid stall-free accelerations and optimises fuel consumption at partial power
conditions.
The variable geometry system components include:

Inlet Guide Vanes (IGV) in the front frame

Stage 1 and 2 VSV

Three sets of lever arms attached to the individual vanes and the three actuating rings.
The variable geometry components are moved by a piston actuator within the Fuel Metering
Unit (FMU) and synchronised by a crankshaft. The actuator is positioned by a servo system
(fuel pressure) within the FMU.
The compressor or gas generator speed (Ng), compressor inlet temperature (T2) and physical
position of the variable geometry actuator provide feedback to the Electronic Engine Control
Unit (EECU) which responds by re-altering the FMU demand.
Issue No 8.0
18/10/2016
Page 39
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.4
Anti-icing and Start Bleed Valve
The Anti-icing and Start Bleed Valve (AISBV) is mounted on the left side of the engine. It has
two functions that are accomplished in a single component:

The start bleed valve is a modulating valve actuated by a connecting link to the variable
geometry crankshaft.

The anti-icing mode is selected with a cockpit switch.
The two functions are distinct. The start bleed is controlled automatically by the EECU via FMU
and the mechanical linkage to the variable geometry system, which is physically connected to
the AISBV. The anti-icing is controlled directly by a pilot command.
Anti-icing System
Anti-icing is accomplished by a combination of hot axial compressor discharge air and heat
rejection from the air/oil cooler integral to the main frame. The hot air anti-icing system is
controlled by an external electrical signal which triggers a solenoid operated air valve.
When electrical power is applied to the valve solenoid, anti-icing is turned off. With electrical
power interrupted off, the valve opens and reverts to the anti-icing mode.
Issue No 8.0
18/10/2016
Page 40
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.5
Cooling Pipes
Secondary airflow is used to cool the C-sump by means of a single pipe on the right-hand side
of the engine at the 4 o'clock position, it also provides air to pressurise the engine labyrinth
seals.
A P3 air tapping is also provided via a single pipe to provide cooling air to the turbine blade
shroud.
At the base of the B-sump there is a leakage pipe from the B-sump pressurisation that is fed
into the C-sump cover.
Around the outside of the turbine casing is a secondary cooling shroud that contains access
holes on top with bucket type containers underneath.
Cooling of the turbine casing is achieved from the engine bay air being induced through the
shroud and distributed by the buckets (venturi effect).
Issue No 8.0
18/10/2016
Page 41
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.6
Air System Sensor (T2)
On the rear face of the IPS scroll case is the housing for the (T2) temperature sensor. The
sensor monitors the temperature of the air passing through the inlet particle separator and
passes the data as an electrical signal to the EECU for fuel scheduling calculations and correct
operation of the variable geometry system.
Issue No 8.0
18/10/2016
Page 42
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.7
Air System Sensors (P3)
There are two air pressure sensors mounted on the right side of the engine accessory gearbox,
inboard of the starter motor mounting pad.
The sensors detect the air pressure in the combustion section of the engine (P3) and pass the
data as electrical signals to the EECU.
Issue No 8.0
18/10/2016
Page 43
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
10.1.8
Air System Sensors (P0)
A single (P0) sensor is mounted on the left of the accessory gearbox near the inlet particle
separator blower. It detects the air pressure within the engine bay and passes the data as an
electrical signal to the EECU.
Issue No 8.0
18/10/2016
Page 44
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
11
Air Module Operation
11.1
Operation of the Engine Air System
11.1.1
Operation
Primary Airflow
The primary airflow is controlled by the IGV and VSV so that the airflow arrives at each
compressor stage at the optimum angle for all compressor speeds. The IGV and VSV are part
of the variable geometry system, which is controlled by the EECU depending on Ng and T2.
At compressor speeds below 87%, the FMU actuating system also positions the starting bleed
valve in the open position.
Secondary Airflows
Stage 4 bleed-air is taken through one external tube to the C-sump. This air cools the C-sump
outer case and pressurises the labyrinth seals at the forward end. This air also forms a "balance
piston" between the power turbine rear and the front of the C-sump case which reduces the
loading on the power turbine thrust bearings.
Stage 4 bleed-air is taken through an internal passage to the B-sump. This air cools the B-sump
case and pressurises the labyrinth seals at either end.
Stage 5 bleed-air is used for the Air Conditioning system and for anti-icing air supply through the
AISBV to the inlet frame vanes and the IGV.
Inside the engine, stage 4 air is used to pressurise the A-sump front seal.
Issue No 8.0
18/10/2016
Page 45
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
Fully pressurised compressor air (P3) cools the surfaces of the combustor liner.
Air which enters the A, B and C-sumps through the seals is vented to atmosphere through the
centre of the driveshafts.
Issue No 8.0
18/10/2016
Page 46
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
11.1.2
Monitoring
Operation of the engine air system is monitored by air temperature and pressure sensors.
Two P3 sensors are located on the accessory gearbox, they sense air pressure from two
individual tappings located on the top of the engine midframe. Each sensor provides
compressor discharge air pressure information to the individual EECU control channels.
The single P0 sensor located on the accessory gearbox, monitors engine bay ambient pressure
(altitude) and provides a back-up control signal to EECU should it loose altitude data from the
aircraft systems.
A T2 sensor located on the back of the IPS scroll case monitors the temperature for the air
entering the engine, it then delivers that information to the EECU control channels, therefore
fuel scheduling is adjusted to compensate for inlet air temperature.
AISBV Operation
The AISBV dumps stage 5 bleed-air through the anti-ice ducting when the engine is operating at
low Ng (below 87%). This offloads the compressor and reduces engine airflow instability.
As Ng increases, the EECU sends a command signal to the FMU which closes the IGV and
VSV which because of a mechanical linkage closes the bleed valve in the AISBV, preserving
stage 5 air for engine power and cabin conditioning.
Should the pilot select anti-icing on from the cockpit controls, the AISBV partially opens to allow
hot stage 5 air into the inlet frame and the IGV/VSV to prevent icing.
Issue No 8.0
18/10/2016
Page 47
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12
Engine Control Module
12.1
General Overview
12.1.1
Engine Control Introduction
The engine controls system can be subdivided into two distinct areas:

Controls in the cockpit to request engine conditions, for example control panel

Controls that govern the operation of the engine, for example Electronic Engine Control
Unit (EECU).
Together the controls system dictates the operation of the engine, the control panel inputs
manual commands to the engine whilst the EECU carries out the commands and normal
operating automatically without intervention from the operator.
Both the control panel and the EECU integrate with the aircraft systems by means of the Aircraft
and Mission Management System (AMMS) for indicating, control and monitoring purposes.
Issue No 8.0
18/10/2016
Page 48
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.1.2
FADEC Introduction
The basic engine control is governed through a dual channel Full Authority Digital Electronic
Control (FADEC) system. The FADEC system is composed of an EECU and a Fuel Metering
Unit (FMU). The EECU contains all computations and control laws and has the full authority to
vary all control inputs to the engine throughout their full range.
Engine performance is mainly achieved by controlling engine gas generator speed (Ng), ITT,
Tq, free power turbine speed (Nf), aircraft rotor speed (Nr), with engine fuel flow and scheduling
compressor variable geometry/compressor start bleed valve positions.
The engine control laws and operational logic functions are coded into the EECU software.
The control system receives inputs from aircraft sensors and cockpit switches and provides
indications, warnings, and diagnostic/failure information to the pilot.
Issue No 8.0
18/10/2016
Page 49
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.2
Engine Control System Architecture
12.2.1
Engine to Cockpit Interfaces
Engine Control Panel
The panel contains the ENG MODE switch and the TRNG guard push button that control the
operation of the engine. The ENG MODE is a rotary switch that selects the engine mode and
controls the fuel solenoid valve. The TRNG guard push button enables the One Engine
Inoperative (OEI) training mode when pushed.
Miscellaneous Control Panel
This panel contains the LD SHARE switch and the 1 ENG 2 A/ICE-INTAKE switches. During
operation in FLT, the two engines share load by either matching torque (Tq) or Inter turbine
Temperature (ITT). The load share mode is selected by the pilot selectable switch. The 1 ENG 2
A/ICE-INTAKE switches allow the pilot to activate the anti-icing systems as required.
Linear Variable Differential Transformers (LVDT)
The angle of the collective (pitch) lever is measured and provided to the EECU.
Collective Grip
The grip contains the AEO LIM SEL switch and the OEI SEL switch. These switches enable the
pilot to select the All Engines Operating (AEO) and OEI limits as required.
Issue No 8.0
18/10/2016
Page 50
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.2.2
Engine Control Architecture
The architecture of the engine control function for the two engine systems is the same.
Cockpit selectable controls request the demanded operation (for example starting) through the
EECU. Each EECU uses pin recognition features in the electrical connections to determine
which engine it is controlling, and shares Tq data with each other's EECU, through a crossengine datalink.
Similarly, each EECU uses digital datalinks to communicate data to the Cockpit Display System
(CDS) and AMMS, which in turn communicate with each other.
Issue No 8.0
18/10/2016
Page 51
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.3
Engine Control System
12.3.1
Engine Control Panel
The engine control panel is installed in the interseat console and performs the following
commands and indications:

ENG 1(2) MODE switch - selects the mode for engines 1 or 2, either OFF, IDLE or FLT. It
also controls the operation of the engine fuel solenoid valve.

TNG guard push button - enables the OEI training mode, provides a green light indication
ON when selected.

CRANK momentary switch - selects the engine 1 or 2 crank function.
Issue No 8.0
18/10/2016
Page 52
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.3.2
Miscellaneous Control Panel
The lighting and miscellaneous control panel is installed in the interseat console and performs
the following engine commands and indications:

TEMP/TORQUE LD SHARE - a two-position switch that allows the pilot to select the load
share mode, by either matching the engines in Tq or ITT.

1 ENG 2 A/ICE-INTAKE - switches that allow the pilots to activate the engines and intakes
anti-ice protection systems independently. There are three positions:
o
o
o
FULL (engine bleed-air anti-ice and intake anti-ice ON)
A/ICE (engine bleed-air anti-ice only ON)
OFF.
(Nota:In the air only, the Anti Icing Start Bleed Valve (AISBV) will not be open by the EECU
if OAT is above 15°c +/- 3)
Issue No 8.0
18/10/2016
Page 53
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.3.3
Engine Power Collective Anticipator LVDT
The angle of the collective (pitch) lever is measured and provided to the EECU by means of two
independent dual coil LVDT.
The EECU use the informations provided by the LVDTs to optimise engine response to the
varying power demands requested by the aircrew. At the engine/aircraft interface each channel
(A and B) of the EECU will provide an excitation signal and receive a feedback signal from the
LVDTs.
Issue No 8.0
18/10/2016
Page 54
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.3.4
AEO and OEI Limit Switches
AEO Limit Select Switch
The EECU will accept an AEO limiter command from a momentary switch on the pilot/co-pilot’s
collective lever. The EECU, when initialised, selects the Max OEI limits. Thereafter, pushing the
AEO LIM SEL button once during AEO operation will cause a switch to AEO take-off limits for
ITT, Ng and Tq. AEO TOP LIM advisory message will show. Nevertheless in case of Nr drop
(Nr<97%) the OEI MAX limits are AUTOMATICALLY selected by the EECU until Nr reach
102%.
Pushing again will cause a switch back to Max OEI limits, and so on.
Note: In OEI conditions or an engine in ENG GOV LOSS mode , Max OEI limits will be selected
without regard to operation of the switch.
OEI Continuous Rating Select Switch
The EECU will accept an OEI limiter command from a momentary switch on the pilot/co-pilot’s
collective lever.
The EECU, when initialised, selects the Max OEI limits. During OEI operating, pushing the
button once will select OEI continous rating limits (OEI MCP=135%TQ). OEI MCP LIM
advisory message will be dispayed. Pushing again will cause a switch back to Max OEI limits
(164%TQ during 30s and automaticaly (if NR>95%) will reduce to 155%TQ or MAX NG,ITT
OEI), and so on.
Issue No 8.0
18/10/2016
Page 55
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
12.3.5
Electronic Engine Control Unit
The primary component of the FADEC is the EECU, which is mounted on the bottom of the
engine.
The EECU consists of two identical control channels which carry out the control computing
functions:

Channel A (blue cable)

Channel B (green cable).
The use of two identical control channels gives full redundancy for all the control functions.
Most control inputs, sensors and power supplies are duplicated, channel A receives engine
inputs through the blue electrical harness while channel B receives inputs through the green
harness.
Where inputs are not duplicated the control channels share data through a cross channel
datalink.
One channel is the "master" control channel, while the other channel is in "Hot standby". The
hot standby channel receives all data and does all the relevant calculations, but its control
outputs are inhibited (except OVSP protection). The choice of master control channel is fully
automated,each starting the channel in hot stand by become channel in control,this to detect a
possible dormant failure.
Issue No 8.0
18/10/2016
Page 56
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
13
Engine Control Components
13.1
Engine Electrical System Components
13.1.1
Engine Np (Nf) Sensor
Two Tq/Np (Nf) sensors are located in the exhaust frame.
The power turbine shaft is equipped with two pairs of teeth which induce electrical pulses in the
sensors. These teeth permit measurement of the torsion (twist) of the shaft, which is
proportional to output Tq, and the speed of the power (free) turbine Np (Nf).
Issue No 8.0
18/10/2016
Page 57
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
13.1.2
Thermocouple Harness
The ITT (T4.5) thermocouple harness is a one-piece assembly consisting of seven single
immersion, equally spaced thermocouples for measuring ITT.
During normal operation a weighted average is computed in the software so that the engine
operates on the average of all seven probes.
Issue No 8.0
18/10/2016
Page 58
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
13.1.3
Permanent Magnet Alternator
The gas generator driven Permanent Magnet Alternator (PMA) is mounted on the front face of
the accessory gearbox. Since the PMA is driven by the gas generator, the frequency of its AC
output is proportional to Ng, so the power supply frequency is also used for the Ng back up
signal to the EECU channels, there is also a hardwire link from the EECU to the cockpit display
this one is called "Ng Analog".
Primary Ng Signal
The EECU receives its primary Ng information from the Ng sensor fitted inside the FMU
adjacent to the main fuel pump. This information is then sent to the cockpit displays by the
ARINC429 databus.
Should the primary system fail in any manner there is a backup signal coming from the PMA to
the cockpit by a hardwired link and for the 2 channels of the EECU.
Issue No 8.0
18/10/2016
Page 59
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
14
Engine Control Operation
14.1
General Overview
14.1.1
Introduction
The engine can be operated in the following modes.
All Engines Operating (AEO)
The aircraft has both engines running in FLIGHT drive.
The AEO has two distinct limits:

Maximum continuous (max con) and take-off (5 minutes).
One Engine Inoperative (OEI)
The OEI allows the continuation of the flight after the failure or shutdown of one engine.
OEI has two limits of operation:

Continuous

2,5 minute
In general, safe OEI flight is defined as:

A sustainable airspeed of not less than 50 KIAS.

The ability to obtain a positive rate of climb at acceptable power levels.

An altitude which provides sufficient clearance from the ground/obstacles so that required
manoeuvring can be reasonably achieved.
Issue No 8.0
18/10/2016
Page 60
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
14.1.2
Engine Power Ratings
Rating
Max Np
%
Max Ng
%
Max ITT
°C
Max Tq
%
AEO Max Continuous
104
102.7
942
100
AEO Take Off (5 Min)
104
102.7
968
116
AEO 5 Sec Transient
105
103.2
974
123
OEI Max Continuous
104
102.7
968
135
OEI 2.5 Min (See Note)
104
105
1078
136 to 164
OEI 5 Sec Transient
105
105
1081
171
Note: Max 30 Sec above 155%. Only one excursion above 155% permitted for each 2,5 min
occurrence.
Issue No 8.0
18/10/2016
Page 61
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
14.1.3
Overspeed/Shutdown System
The EECU provides an independent overspeed/shutdown system, which close the overspeed
valve in response to a detected engine Ng or Np overspeed or in response to the Stop/Idle/Fly
knob being set to STOP.
There are separate overspeed/shutdown systems in each channel of the EECU (harware and
Software) and both systems are active all the time. Therefore the channel not in control at any
time provides completely independent overspeed protection for the channel in control.
The overspeed trip points are:

Ng overspeed 108.5%

Np overspeed 119%.
The overspeed system is non-latching and will restore fuel flow (overspeed valve re-open), turn
on ignition and attempt to relight the engine as soon as speed falls below the trip speed.
If the EECU detects a broken power turbine shaft (Tq<5%) during an overspeed event, the
relight function is disabled. So the engine will shutdown automatically. In case of OEI condition
the overspeed protection is always ensured.
Issue No 8.0
18/10/2016
Page 62
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
14.1.4
Training Mode
The training capability allows pilots to train under simulated OEI conditions at actual OEI power
levels without impacting the life of the engine. This is achieved by running both engines at
reduced power levels so that the operation of the two engines together simulates OEI operation.
Since normal training operation is accomplished by reducing power of both engines, there is no
difference in engine operation between a simulated failure of engine 1 and a simulated failure of
engine 2. Note also that all output signals from the EECU will reflect actual engine operation
and will not be biased or altered to reflect the simulated failure situation.
When there has been a valid entry into training, both engines will decelerate in a manner
intended to represent as closely as possible, without violating engine operating limitations, a
single engine flameout. At the same time a Tq limitation will be imposed on both engines to
simulate the levels that would be experienced for single engine operation in an actual OEI
situation.
OEI Training can be SELECTED with this following conditions:

Push the momentary AEO LIM switch, this will enforce the AEO limits

NR nominal.

EECU in good condition (no significant failure).

Push the momentary TRAINING switch, this will enforce the OEI TRAINING function.
While in training the OEI limit switch will select the different OEI limits,either OEI continous or
max.
Issue No 8.0
18/10/2016
Page 63
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
If at any time during training operation, there is a loss of one engine, a significant failure in the
engine control systems, or Np (Nf) droops below 87%, the two engines will automatically exit
training and return to normal operation. If there has been a loss of one engine, the remaining
engine will be max OEI limits.
Training mode is used to allow simulation of operation in an OEI situation without actually being
in OEI:

Each engine is operated at a power of half of that expected by a single engine in OEI –
both engines operate identically
o

Engine limits to the lower value of Tq, Ng, or ITT limits
o
o

Transient on entry into training is designed to approximate transient for actual entry
into OEI
Engine Tq limits = half single engine OEI Tq limits
Other engine limits (Ng/ITT) = half single engine OEI
Difference in operation on different limits
o
o
On Tq limit, speed droop does not increase Tq
On Ng/ITT limit, speed droop increases Tq to keep constant power.
Training Mode Indication
When the OEI training mode is selected by the pilot and authorised by the EECU, the Power
Index (PI) and triple tachometer scales are arranged to show the de-rated engine power limits,
regardless of the active Primary Flight Display (PFD) format. Furthermore, the size of Nr
readout is increased to enhance its readability.
The OEI training mode is enabled according to the predefined EECU control laws and the OEI
legend is displayed.
A TNG (training) legend is vertically displayed in amber at the bottom of pertinent PI scale, while
the Ng, ITT or Tq transient limits are suppressed.
When the OEI training mode is active, the OEI power on Vne limit is displayed as a red/white
symbol on the airspeed tape.
Note: The training mode logic uses twin-engine power to simulate single engine characteristics
and has been optimised for CAT A training.
Issue No 8.0
18/10/2016
Page 64
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
14.1.5
EECU Fault Management
Each EECU channel performs fault identification and management to allow the FADEC system
to maintain engine control. The EECU manages component failures in the following manner:

A 1(2) EECU MAINT caption will result in a non fully operational control system that has a
channel not fully operationnal.
o
o
o
o
In reversionary mode, indicated by two different CAS warnings messages, the EECU
has detected failures. This mode is divided into two categories that are displayed:
1 (2) ENG PWR LIM , which will limits the maximum power aviable from the engine.
1 (2) ENG SLOW RESP , which reduces the rate of acceleration/deceleration during a
transient manoeuvre.
1(2) ENG GOV LOSS indicates a total loss of FADEC control. This mode allows
continued operation of the engine with either a restricted variation of power or all
commands "frozen". The engine may then be operating at a fixed power level or not
regards to the system in trouble (VG,metering valve command or both in trouble).
Issue No 8.0
18/10/2016
Page 65
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
15
Engine Indicating Module
15.1
Purpose of the Engine Indications
15.1.1
Engine Indications Introduction
Engine indications are displayed in the cockpit on the Display Units (DU)
The informations are shared between PFD, MFD Power Plant page and Engine Apu Fuel
synoptic page.
Trought the ECDU the crew can test some systems in relation with the engine (Fire and Air
intake anti icing test).
Issue No 8.0
18/10/2016
Page 66
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
15.2
Engine Indicating Architecture
15.2.1
Description
The EECUs receive and transmit digital information by means of Arinc 429 serial data bus
communication.
Each EECU channel transmits from its own Arinc 429 transmitter, and both of them has two
receivers as well.
Engine data are then transmitted to both AMMCs and all four DUs. The AMMCs then by means
of AFDX high speed data bus, provide engine data to all four DUs.
Issue No 8.0
18/10/2016
Page 67
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16
Controls and Indications
16.1
Description
16.1.1
Engine Display
All engine operating information is displayed in the cockpit on the PFD and the MFD.
The PFD displays:

Power Index (PI) - torque (TQ) values and indications for the two engines

The triple tachometer which displays the free power turbine (NF) and main rotor (NR)
information.
In the PFD composite format the PI and triple tacho information would be displayed as well as
the engine secondary data and engine oil pressure data.
On the map, plan and other system pages on the MFD, the engine secondary data for engine oil
pressure and temperature is displayed. If the power plant page is selected then the engine
secondary data oil pressure and temperature are displayed as well as the triple tacho and all of
the engine primary data (NG, ITT and TQ).
Issue No 8.0
18/10/2016
Page 68
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.2
Power Index
The purpose of Power Index (PI) is to obtain a substantial reduction of pilot workload in order to
increase the safety of flight. It is a single instrument shown on the PFD.
This instrument is computed by the AMMCs. Thanks to this device, the pilot can monitor all four
engine parameters in one indication. The PI provides the available power based on the lower
limiting engine parameters. Those parameters are legend on the top of the PI.
They are Torque (TQ), Turbine Temperature (ITT) Gas Generator speed (NG) and Corrected
Gas Generator speed (NGc).
On the scale, it is shown the TQ mechanical (if the TQ is displayed on the top legend) or
equivalent regarding the remaining power limiting parameters (ITT, NG). Concerning the NGc a
cyan line will appear on the scale as soon as the engine will reach this limit.
Three different engine ratings are computed, one for All Engines Operating (AEO), one for One
Engine Inoperative (OEI) and one for One Engine Inoperative Training (OEI TNG).
Display of the above information on each engine side occurs independently from each other and
is prioritized from the highest to lowest TQ, ITT and NG.
The OEI mode is active when one engine fails or is not capable to deliver power.
Issue No 8.0
18/10/2016
Page 69
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.3
Power Index Indicator (PI%)
All Engines Operating (Airspeed below 90 KIAS)
Maximum Continuous Operation
100
30 min Torque Range
101 to 116
5 min Engine Range
101 to 116
Maximum 30 min / 5 min
116
Transient 5 seconds (TQ)
123
All Engines Operating (Airspeed above 90 KIAS)
Maximum Continuous Operation
100
Cautionary Range (Temporary Excursion)
112
Transient 5 seconds (TQ)
123
One Engine Inoperative
Maximum Continuous
135
2.5 min Range (TQ)
136 to 164
(Max 30 sec above 155)
Note:
The Automatic Power Reduction will reduce the torque available to 155% after
30 seconds of cumulative time above 155% TQ is achieved.
2.5 min Range (NG or ITT)
136 to 164
Transient 5 seconds (TQ)
171
Issue No 8.0
18/10/2016
Page 70
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.4
Rating Legend
AEO 5 m is displayed in amber on PI showing that associated engine is on final 5 minutes from
exceeding AEO 5 minutes engine rating or AEO 30 minutes transmission rating. Same label is
displayed on MFD between NG and ITT scale for engine rating limits or beside the TQ scale for
transmission rating limit.
The label become flashing and in inverse video when the above limit is within 10 seconds from
expire and will show steady when either AEO 5 minutes engine rating or AEO 30 minutes
transmission limit have been exceeded.
The same logic applies for OEI 2,5 m . CAS message 1(2) ENG LIM EXPIRE will shows when
the indication is within 10 seconds from exceeding OEI 2,5 minutes engine or transmission limit.
When the limit is in the 30 seconds TQ range, the 2.5m message is moved down, changed to
grey and replaced by the 30sec countdown timer.
OEI 29s countdown is displayed in amber on side of PI digital value to indicate the time
remaining in the transmission rating. The label become flashing in inverse video when OEI 30
seconds transmission rating is within 10 seconds from exceeding and will show steady when
limit expired. When the limit is expired, the EECU automatically reduces power below 156% TQ
unless the rotor droop below 95%. In this case the power will be reset to 164%.
In case the 30 seconds TQ range is exited, the countdown timer is moved down, changed to
grey, value frozen and replaced by the 2.5 min message.
Issue No 8.0
18/10/2016
Page 71
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.5
Rotor Droop Threshold
To allow the aircrew to identify when the engine is limited by NGc, an additional independent
cyan line is shown onto the PI display. The cyan line represents the physical NG speed
calculated with the current ambient atmosphere in order to provide a fixed limit of 104% NGc.
The cyan line will change its position as the ambient condition changes.
When operating in AEO or Training Mode, the NGc cyan line is positioned on the PI display so
that it represents the engine with the lowest value of ‘NGc’ (i.e. the engine that will limit last).
When operating OEI the NGc cyan line is positioned on the PI display so that it represents the
NGc for the functional engine.
When the NGc cyan line on the PI display aligns with the PI indicators, the engine will be limited
by NGc. When the NGc cyan line is above the PI indicators the engine will be limited by either
the main transmission or the engine ITT or Ng.
When the limiting engine parameter pointer is at the same position as the cyan bug further
power demand will result in rotor droop due to the fact that the engine cannot provide any more
power being limited by the compressor performance. In this case the EECU will protect the
engine
Issue No 8.0
18/10/2016
Page 72
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.6
OEI Training Mode
The engine training mode incorporated in the engine EECU simulates an engine failure and
corresponding single engine response and rotor speed characteristics as in an actual engine
failure.
When the Training Mode is selected by pilot, the PI and NF displays on the PFD, are artificially
configured to display one engine as ‘inoperative’ and the engine in OEI TNG as the sum of the
two engine PI (TNG legend is vertically displayed in amber on the side of the engine in OEI).
On the P-PLANT page of the MFD, the actual engine parameters are displayed while on the
NR/NF indicator for the PFD and MFD the coloured ranges are modified, from AEO to OEI, to
allow NR/NF droop to 90% as required by the CAT A procedure.
With this display the PFD presents the simulated OEI condition while the MFD, for safety
reasons, presents the real AEO conditions.
When the OEI training mode is active, the OEI power on Vne limit is displayed as a red/white
symbol on the airspeed tape.
Issue No 8.0
18/10/2016
Page 73
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.7
Typical Engine Scales
The primary electronic displays clearly inform the crew of the current flight condition and the
status of flight guidance, flight control, navigation and aircraft systems, and provide information
required to control the aircraft and monitor its progress with respect to the desired flight path.
This information is presented with the accuracy, legibility and readability required for error free
control of the aircraft in all workload conditions.

The top of the scale indicates the scale parameter being indicated.

Digital readouts are used and integrated with an bargraph display, this provides a precise
quantitative indication to complement the bargraph.

A horizontal red line is used to separate the red band (mark) from the other adjacent
coloured bands (green or amber). All the red lines shall be located at the same scale length
in order to provide a "normalised" visual cue.

The shape of the pointer used for the primary engine indications (NG, ITT, TQ, NR, NF, and
PI) is a moving solid triangle connected with a vertical line to the bottom reference line. This
helps to assess the trend of various parameters and the matching between the two engines
data.

The shape of the pointer used for the secondary power plant indications is a moving solid
triangle, except for the oil temperature indications, which are moving T-shaped symbols.

A red triangle with a horizontal red line is used to indicate a transient limit on some specific
analogue scales.

A half red dot with a horizontal red line indicates the HOT START LIMIT on the InterTurbine
Temperature (ITT) scale. This symbol is only displayed during engine starting or in-flight
relight.
Issue No 8.0
18/10/2016
Page 74
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot

Coloured bands within the scale indicate the state of the parameter:
o
o
o
Green for normal operating area
Amber for the cautionary area, this may be time limited
Black for a turbulent area that should not be loitered in, often referred to an avoid band.
Issue No 8.0
18/10/2016
Page 75
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.8
Engine Synoptic Format
The engine synoptic format accessible from a drop down menu on the MFD, provide the
operator with graphical information concerning the status of the engine system.
In the engine synoptic format are displayed:

The EECUs and their channel status

Engines silhouette with main parameters (NF, ITT, NG, TQ)

Oil temperature and pressure scales

Fuel lines from helicopter fuel system

Engine status and degraded mode

Power check result.
Issue No 8.0
18/10/2016
Page 76
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.1.9
MFD Engine Primary Parameters
Other indications for the engine that could be displayed are:

On the MFD, AEO configuration with an NR discrepancy.

Start and Ignition during the start sequence and an NF 2 not received.

OEI (One Engine Inoperative) indication when a single engine is not running. OEI TNG may
also be display if the crew have selected the engine in training mode.

Should any of the parameters be exceeded the pointer will infill with the appropriate colour
(red/amber).

If this a time limited area the countdown limit will be displayed in amber. If this limit is
approching a red blinking box will suround the time counter and if the crew exceeded the
limit will be surrounded by a red steady box.
Issue No 8.0
18/10/2016
Page 77
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.2
Engine Indications Warnings and Cautions
16.2.1
Engine Warnings
CAS Message
1(2) ENG OUT
Description
Engine NG below 50% or NG rate of change outside
predetermined limits.
Aural Tone "ENGINE 1(2) OUT"
1(2) ENG OIL P LOW
Low oil pressure in associated engine (less than 1.4 bar).
Aural Tone "WARNING"
1(2) ENG IDLE
Associated engine at IDLE and collective being raised
(triggered on ground only)
Aural Tone "ENGINE 1(2) IDLE"
1(2) ENG FIRE
Associated engine fire or hot gas leakage detection
Aural Tone "ENGINE 1(2) FIRE"
1(2) ENG GOV LOSS
Automatic reversion of associated engine to fixed engine
power
Aural Tone "WARNING"
Issue No 8.0
18/10/2016
Page 78
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.2.2
Engine Cautions
CAS Message
1(2) ENG SLOW RESP
1(2) ENG PWR LIM
1(2) ENG OVSPD
Description
Associated engine operation degraded and possible slow
response.
Associated engine operation degraded and possible limited
power.
Associated engine NF overspeed triggered.
1(2) OVSPD TEST FAIL
Associated engine NF overspeed system self test failed.
1(2) HOT START
Associated engine ITT limit exceeded on engine starting.
1(2) ENG OIL FILTER
Associated engine oil filter in bypass condition.
1(2) ENG OIL P HIGH
Associated engine oil pressure above the limit.
1(2) ENG OIL TEMP
Associated engine oil overtemp (greater than 132 °C).
1(2) ENG OIL CHIP
Associated engine chip detected.
1(2) ENG A/ICE FAIL
Anti-ice valve is not open when Anti Ice is demanded by the
crew AND the engine is not declared out, or Anti Ice valve
remains open with anti-ice bleed selected OFF.
Issue No 8.0
18/10/2016
Page 79
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.2.3
Engine Cautions Continued
CAS Message
Description
ENG PANEL FAIL
Engine control panel failed.
1(2) EECU DATA
Associated engine data not being received by the AMMCs.
1(2) EECU MAINT
Associated engine control unit internal fault.
1(2) EECU OVERHEAT
Associated engine control unit overheating
1(2) EECU DEGR
1(2) ENG LIM EXPIRE
Associated engine control degraded
Associated engine exceeded 2,5 min OEI ratings
(ITT/NG/TQ).
1(2) FUEL FILTER
Associated fuel filter blocked and impending bypass
condition.
1(2) NG MISCOMPARE
Discrepancy between EECU and analog value of NG
Issue No 8.0
18/10/2016
Page 80
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
16.2.4
Engine Advisories
CAS Message
Description
AEO TOP LIM
AEO LIM SEL pushbutton selected on collective and AEO
limiter ON
OEI MCP LIM
OEI SEL pushbutton selected on collective and MCP limiter
ON
Issue No 8.0
18/10/2016
Page 81
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
17
Engine Exhaust Module
17.1
General Overview
17.1.1
Introduction
Each engine exhaust is made of an exhaust ejector and nozzle assembly. The nozzle assembly
is made of:

A lobed primary diffuser

A coned centre body
The lobed diffuser and centre body are engine mounted and the ejector is directly supported by
the rear sliding fairing assembly.
The engine exhausts are completely independent from each other.
The exhausts are fabricated from titanium, and are designed to ensure ventilation of the
engines bays and direct exhaust gases away from the main rotor blades and fuselage structure.
The entire exhaust system is located aft of the engines air intakes, fuel system components,
and bay drains.
Issue No 8.0
18/10/2016
Page 82
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
17.2
Engine Exhaust Components
17.2.1
Exhaust Nozzle
The exhaust nozzle assembly is mounted directly to the engine by means of a Vee-band clamp,
it is maintained in the correct position on the engine by a spigot at 12 o'clock position.
The nozzle assembly is designed to so that it removes some of the energy from the airflow and
correctly guides it into the ejector assembly. The centre cone protects the C-sump cover and
acts as a guide path for any internal air leakage coming from the engine.
Issue No 8.0
18/10/2016
Page 83
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
17.2.2
Exhaust Ejector
Each ejector is designed to direct the exhaust gas flow from the engine and to minimise the
possibility of trapped fuel.
All fluids draining from the exhausts are conveyed into the engine bay and further drained
through dedicated engine bay drains.
There are exhaust ejectors within the rear sliding fairing that direct the hot gases from the
primary nozzle away from the aircraft.
The rear sliding cowling area around the exhaust ejectors is fabricated from fire resistant carbon
fibre. The ejector is mounted to the forward firewall of the sliding fairing and also via two
attachment points within the sliding fairing which permit thermal expansion.
Issue No 8.0
18/10/2016
Page 84
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
18
Engine Oil Module
18.1
Engine Oil System Purpose
18.1.1
Lubrication System Introduction
The lubrication system in the CT7-2E1 engine distributes oil to all moving parts of the engine
that require it.
The system is a self-contained, recirculating, dry sump system. Maximum oil consumption is 0,3
lb/hr.
Issue No 8.0
18/10/2016
Page 85
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
18.2
Oil System Architecture
18.2.1
Description
The engine oil system design provides:

Seal pressurisation by air and sump venting

Emergency oil supply system

Oil filtration and condition monitoring

Oil temperature and pressure monitoring.
To enable the system to provide these functions a number of components for operation, and a
number for sensing are required to make it operational.
The engine oil system consists of the following subsystems and components:

Lube and scavenge pump

Scavenge screens and filters with bypass

Oil tank

Oil cooler

Oil cooler bypass/relief valve

Chip detector

Pressure and temperature sensors and switches.
Issue No 8.0
18/10/2016
Page 86
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19
Engine Oil System Components
19.1
Description
19.1.1
Oil Tank
The engine oil tank is an integral part of the front frame of the engine. Oil level visual indicators
(sight glasses) are located on each side of the tank. The tank holds approximately 6.9 litres of
oil which is sufficient to lubricate the necessary bearings and gears.
The tank is filled through a gravity filler point on the right side of the engine, if an oil overflow
occurs during this operation, the spilled oil enters a drain, which exits the engine at the common
drain point immediately below. This common drain is also the exit point for any oil leaked from
components attached to the engine accessory gearbox.
Oil supply to the lubrication pump is through a coarse screen which is removable through the
forward tank wall. Below this screen is the tank drain plug.
On the bottom of the inlet frame is the exit point for the front frame and axis G drains.
Issue No 8.0
18/10/2016
Page 87
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19.1.2
Lubrication and Scavenge Pump
The lubrication and scavenge pump assembly is a gerotor type pump containing one supply
element and six scavenge elements. The pump assembly is installed in the front face of the
engine accessory gearbox.
Oil leaving the supply element is passed through a 3 micron filter and passes through passages
in the accessory gearbox where the flow divides to supply oil to the various places which need
it.
Issue No 8.0
18/10/2016
Page 88
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19.1.3
Oil Filter
Oil discharged from the supply element of the lube and scavenge pump assembly passes
through a passage in the accessory gearbox to the oil filter.
The oil filter is of the disposable element type and has a very high degree of filtration.
Close to the oil filter is the oil filter bypass switch which detects increasing differential pressure
across the filter and outputs an electrical signal at a preset threshold of 60-80 psi (4,1-5,4 Bar).
1(2) ENG OIL FILTER will occur before the filter's internal bypass valve opens. A springloaded, poppet type, cold oil relief valve is incorporated in this system to prevents excessive
supply pressure during cold starts, when high oil viscosity creates high system pressures.
Cracking pressure is set for 120-180 psid (8,1-12,2 Bar) and reset is 115 psid (7,8 Bar)
minimum.
Issue No 8.0
18/10/2016
Page 89
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19.1.4
Oil System Sensors
The engine oil system is provided with temperature and pressure sensors which monitor system
operation.
The oil temperature and oil pressure transmitters send electrical signals for use in the aircraft's
cockpit display system ex:1(2) ENG OIL P HIGH or 1(2) ENG OIL TEMP .
While the low oil pressure switch is an independent sensor which triggers a Crew Alerting
System (CAS) message in the event of engine oil pressure loss 1(2) ENG OIL P LOW.
The engine oil system is arranged so that both the oil pressure transmitter and the low oil
pressure switch detect the pressure across the B-sump, this sump has the lowest pressure
differential and provides the earliest warning of failure.
Issue No 8.0
18/10/2016
Page 90
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19.1.5
Chip Detector
The chip detector is mounted on the front of the accessory gearbox. It consists of a magnet and
two electrical contacts.
Any magnetic metallic particles in this oil will be captured by the magnet and complete a circuit,
which will give an indication in the cockpit: 1(2) ENG OIL CHIP.
Issue No 8.0
18/10/2016
Page 91
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
19.1.6
Oil Cooler
The oil cooler is a series of tubes inside a thin casing. Oil from the chip detector floods the oil
cooler casing, while engine fuel passes through the tubes.
Heat from the oil is therefore transferred into the fuel. Close to the oil cooler is the oil cooler
relief valve, which directs oil directly back to the oil tank if the differential pressure through the
oil cooler is too high.
Issue No 8.0
18/10/2016
Page 92
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
20
Engine Oil System Operation
20.1
Description
20.1.1
Oil System Operation
When the gas generator turns, oil is drawn from the tank through internal passages by the
supply element of the lube and scavenge pump. The supply element pressurises the oil and
pushes it around the system.
From the pump, the oil passes to the oil filter which removes any impurities. If the oil filter
becomes blocked, the oil filter bypass switch gives an indication of impending bypass before the
filter's internal bypass valve opens. Oil from the filter outlet is passed to three sensors. The oil
temperature sensor and the oil pressure sensor send electrical signals to the Electronic Engine
Control Unit (EECU) for display in the cockpit. The low oil pressure switch sends an
independent signal to the EECU which causes a red warning CAS message in the cockpit if the
oil pressure falls below a preset datum value.
Filtered oil passes through internal passages to the accessory gearbox and the A-sump.
External pipes also carry oil to the B and C-sumps. Oil entering the B-sump is held back by the
check valve until the oil pressure rises. This ensures oil cannot enter the B-sump until the
engine has generated sufficient internal air pressure (stage 4 air bleed) to prevent oil escaping
through the labyrinth seals. Oil from the accessory gearbox returns to the tank by gravity
through internal passages.
Oil from the A, B and C-sumps is drawn back to the lubrication and scavenge pump assembly
by the individual scavenge elements of the pump:
Issue No 8.0
18/10/2016
Page 93
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot

A-sump oil returns through two internal passages.

B and C-sump oil returns through external pipes (one for the B-sump, three for the C-sump)
to a common manifold at the rear of the accessory gearbox.
Oil entering the scavenge elements of the pump passes through wire mesh screens (one for
each element, individually labelled for ease of maintenance) which catch any debris coming
from the sump bearings.
From the B-sump scavenge screen, an external pipe (delta tube) is connected to the oil
pressure sensor and the low oil pressure switch. This ensures that these sensors monitor the
pressure drop across the B-sump (which has the smallest pressure drop because of the check
valve and is in the harshest engine environment with the largest temperature changes during
engine operation). These sensors also monitor pump operation, since the supply element of the
pump is at the opposite end of the common driveshaft from the B-sump scavenge element.
From the six scavenge elements of the lube and scavenge pump assembly, oil passes through
a common outlet port to the chip detector. The chip detector sends an electrical signal to the
EECU, which generates the appropriate cockpit indication if a magnetic particle is detected in
the oil flow.
From the chip detector, oil returns to the tank through the oil cooler. The oil cooler transfers
some of the heat from the oil into the engine's fuel system. Oil from the cooler returns to the
tank through webs in the IPS, which adds to the cooling effect and also provides some anti-icing
effect in the IPS vanes and the splitter.
If the oil is cold, a relief valve within the oil cooler inlet bypasses the oil cooler and returns the oil
directly to the tank.
Issue No 8.0
18/10/2016
Page 94
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
20.1.2
Emergency Oil System Operation
In order to allow time for an engine shutdown if the oil supply fails, the A and B-sumps are
provided with an emergency lubrication system. The accessory gearbox and C-sump
components can operate for at least six minutes without residual oil present and are not
required to receive emergency oil.
During normal operation, oil supply to each of these sumps fills a small emergency reservoir
which is built into the sump casing. The oil in this reservoir is constantly being sprayed onto the
bearings through a secondary oil jet which is in parallel with the main oil jet. The secondary oil
jet is powered by stage 5 bleed-air which causes a jet pump effect to provide an air/oil mist.
If the oil supply to the main oil jet fails, the emergency reservoir continues to supply oil to the
bearings for a short period. The main oil jet now provides an air path to the top of the reservoir.
Issue No 8.0
18/10/2016
Page 95
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
21
Engine Starting
21.1
Engine Starting System Architecture
21.1.1
Description
Two GE CT7-2E1 turbo shaft engines provide power to the AW189 rotor system and supply the
mechanical drive for two AC starter generators.
There are two 25 kVA AC starter generators, two Starter Generator Converter Unit (SGCU) sets
and a Starter Rectifier Unit (SRU).
The starter generator is located on the engine accessory gearbox, whilst the SGCU and SRU
are located in the rear avionics cabinet.
The starter generators act as:

The DC electrical starter motor, providing rotation to the gas generator spool via the
accessory gearbox drive

The main source of electrical power for the aircraft when in generation mode.
The SRU converts either 115 Vac external power or 115 Vac Auxiliary Power Unit (APU)
generator power to 270 Vdc power.
The SGCU acts as an interface for the starter, only providing power when told to do so by the
Electronic Engine Control Unit (EECU) and start commands.
Issue No 8.0
18/10/2016
Page 96
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
When the main engines have reached operating speed, the starter generator will provide 115
Vac for conversion to 28 Vdc power through the SGCU.
Issue No 8.0
18/10/2016
Page 97
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
22
Engine Starting Components
22.1
Description
22.1.1
Starter Generator - Location
The starter generator is attached to each engine and driven from the accessory gearbox.
The AC starter generator is an electromagnetic rotating machine capable of converting engine
input mechanical torque into output electrical power and vice versa.
Each starter generator provides 115/200 Vac, 400 Hz, three-phase power.
Issue No 8.0
18/10/2016
Page 98
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
23
Engine Starting Controls and Indications
23.1
Description
23.1.1
Engine Control Panel
Engine starting and stopping is initiated by a control panel on the interseat console, although
the starting sequence is monitored and controlled by the engines' EECU.
The engine mode switch can be moved from OFF, to IDLE, and to FLT by simply rotating
clockwise into the relevant detent.
It can be moved from FLT to IDLE by rotating anticlockwise. In order to move the switch to OFF,
it must be pushed down and rotated.
Issue No 8.0
18/10/2016
Page 99
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
23.2
Engine Starting Indications
23.2.1
MFD/P-PLANT Page
The Multifunction Display (MFD) screen gives an overall view of all the engine and aircraft
system parameters with all scales and limits. During the start cycle the word START will appear
at the side of the Ng scale and the word IGN will appear at the side of the Interturbine
Temperature (ITT) scale during the ignition process.
On the map, plan and other system pages, the engine secondary data for engine oil pressure
and temperature are displayed, as well as all the primary information previously discussed.
If the power plant page is selected then the engine secondary data oil pressure and
temperature are displayed as well as the triple tachometer and all of the engine primary data
(Ng, ITT and Tq).
Issue No 8.0
18/10/2016
Page 100
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
24
Engine Starting Operation
24.1
Description
24.1.1
Engine Starting - Normal
Engine starting requires electrical power from either an external A/C supply or the APU. On
application of electrical power, a supply is sent to the engine control panel, Electrical Control
and Display Unit (ECDU), SGCU, SRU and the EECU.
The fuel Shutoff Valves (SOV) are opened through the ECDU.
The SRU rectifies the 115 Vac into 270 Vdc for supply to the SGCU and in turn to the starter
generator.
To select start the engine mode switch is set from OFF to IDLE, the EECU receives the
command and issues a start enable command to the SGCU to initiate the start cycle. The
SGCU commands the starter generator to turn the engine.
As the starter is connected through an angled shaft to the accessory gearbox, the accessory
gearbox will start to rotate and in turn the compressor shaft will turn. This induces air into the
engine and the compression sequence starts.
As the compressor starts to turn the Ng signal is sent to the EECU which signals the Aircraft
and Mission Management System (AMMS) that start has commenced and the START legend is
displayed on the MFD.
Between 10 - 15% Ng the EECU will command the ignition system to excite and spark, a signal
is sent to the AMMS and the IGN legend is displayed on the MFD at the ITT scale.
Issue No 8.0
18/10/2016
Page 101
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
At 15% Ng approximately the EECU commands the Fuel Metering Unit (FMU) stepper motor in
the metering valve to open and the overspeed valve to open. This allows pressurised fuel
through to the fuel nozzles.
The EECU provides an electrical signal to the variable geometry system and in conjunction with
fuel pressure from the FMU, the variable geometry fully opens allowing maximum air to the
compressor, as this opens a mechanical link opens the start bleed valve to tap off unstable
airflow at the later stages of the engine.
As the engine progressively gains speed the EECU and fuel pressure will close the variable
geometry and start bleed system progressively with speed. At the self-sustaining speed the start
bleed valve will be fully closed and the variable geometry system will operate as per engine
demand.
The start should be monitored using cockpit instrumentation along with visible and audible signs
of rotation.
Engine starting Rotorcraft Flight Manual limitations and conditions requiring the start cycle to be
aborted must be observed (max ITT 963 °C).
The EECU will turn off the starter generator at 51.6% Ng and terminate the start command. If
this is not removed then the SGCU will automatically terminate starting at a pre-fixed RPM
(approx 6900).
The engine will then accelerate up to IDLE.
A normal start occurs when the engine lights up and accelerates to idle speed within ITT limits.
The engine can be restarted at any time after normal shutdown provided the ITT is below 150
°C. GE MM NOTE: ** EECU must be powered to warm up for 10 minutes before engine start at
-40°C
Starter Duty Cycle:
45 seconds on, 1 minute off
45 seconds on, 1 minute off
45 seconds on, 30 minutes off
Issue No 8.0
18/10/2016
Page 102
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
24.1.2
Engine - Crank
Engine cranking is a method of motoring over the engine without fuel or ignition. It enables the
operator to run the engine to:

Clear trapped fuel and vapours following an aborted start

Cool the engine if the ITT is out of limits for start

Carry out compressor washing and checks for maintenance purposes.
The exact same sequence is carried out as the normal start but there is no intervention from the
EECU for fuel or ignition.
To operate the engine in crank mode:

The engine mode switch is set and held to CRANK

Release the engine mode switch when cranking no longer required

You must not crank for more than 45 seconds, the starter duty cycle must be respected.
Note: Observe the starter duty cycle limitations as they apply to both starting and cranking, 45
seconds between starts. The RFM is to be checked for any other conditions.
Issue No 8.0
18/10/2016
Page 103
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
24.1.3
Hot Start Prevention
24.1.4
Hot Start Prevention
The EECU control the engine starting sequence and has a built in safety feature called hot start
prevention.
The engine hot start preventer will always be active when the engine mode select switch is set
to IDLE, however, moving the engine mode switch from STOP to FLT will deactivate the hot
start preventer.
Issue No 8.0
18/10/2016
Page 104
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
24.1.5
Aborted Start Procedures
Engine starting malfunctions are most likely to occur during the engine acceleration cycle to
IDLE speed. The list below details the cockpit indications associated with malfunctions and the
recommended abort procedure. It is important that flight crews and maintainers be thoroughly
familiar with these procedures.
Monitor the engine start and if any of the following occur shut down the engine:

Light up is not within 18 seconds of Ng initial indications

Abnormal noise heard

ITT increases beyond engine limits ( 1(2) HOT START caution illuminated) or start
terminated by engine control at 963 °C

Engine hangs (stagnation in Ng below idle value)

No indication of oil pressure within 30 seconds of ENG MODE to IDLE/FLT

The main rotor has not begun to rotate when the gas generator (Ng) reaches 40%

If engine starter fails to disengage by 52% Ng.
The engine can be shut down engine by:
24.1.6

ENG MODE switch — OFF

FUEL PUMP — OFF

FUEL ENG SOV — CLSD
Restarting Engines
CAUTION
Refer to RFM
Failure to follow the correct abort procedure may cause damage to the engine.
Observe the igniter and starter generator duty cycle limitations
Issue No 8.0
18/10/2016
Page 105
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY
FOR TRAINING USE ONLY
AW189-TR001-SN-I-71
71 - Power Plant
Student Notes - Pilot
24.1.7
Restarting Engines
On Ground
Whenever the engine is shut down without a 2 minute cooling period at ground idle, or 2
minutes with Ng below 90%, this is considered an emergency shutdown. One of the following
procedures must be carried out:

Restart the engine using the normal start procedure within 5 minutes of the shutdown
(provided the reason for the emergency shutdown is known and restart will not cause
engine damage). After a successful start the engine should carry out a normal engine
shutdown with a 2 minute cooling period with the ENG MODE switch selected to IDLE or 2
minutes with the Ng less than 90%.

The engine may be restarted after the engine has been allowed to cool for at least 4 hours,
if a start cannot be made within 5 minutes of the emergency shutdown.
In Flight
Whenever the engine is shut down in flight there is no limitations for restart. The restart should
be with a maximum ITT of 150 °C and Ng below 15%.
If an engine flames out/or is shut down during flight and if there is no indication of a mechanical
malfunction or engine fire, the engine may be restarted.
Issue No 8.0
18/10/2016
Page 106
Use and disclosure of this document is controlled; see Title/Cover page.
FOR TRAINING USE ONLY