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BOEING 767 SYSTEMS REVIEW
Page 1
POWERPLANT
1. GENERAL
¡ Engines: General Electric CF6-80C2 or Pratt & Whitney 4060 (Rolls Royce not studied here)
¡ N1 (Low Pressure) = Fan + Compressor section & Turbine section
N2 (High Pressure & drives engine accessories) = Compressor & Turbine sections
¡ Fan gives 78% of the total thrust. (for information : Reverse on FAN only).
2. EICAS
¡ EICAS (Engine Indication and Crew Alerting System) = 2 CRTs + 2 computers & 1 control panel.
UPPER EICAS Ô N1 & EGT = primary engine parameters
Ô Messages indicating system faults
LOWER EICAS Ô N2, Fuel Flow, Oil Press & Temp., Oil Qty, Engine vibration = Secondary engine parameters
Ô Displayed when : - initially powered
- selected by engine display switch
- either Fuel Cont. switch CUT OFF
Other indications auto display when exceeding the limits.
¡ N1 & N2 have red limits Ô when limit is reached or exceeded, the pointer & the counter become red.
EGT, Oil Press & Oil Temp have amber & red limits Ô First become amber and then become red
¡ EICAS records RPM & EGT exceedance in an Auto Event Memory (displayed in smaller white numbers below
the actual value counter).
¡ EICAS compacted mode is displayed in case of single CRT failure.
Auto activation of the Standby Engine Indicator (SEI) if AUTO position is selected and if :
- AC power is lost
- Either CRT failed & STATUS selected on the ground
- EICAS failed
¡ Automatic call-up in case of parameters exceeding the limits.
- if STATUS selected after, exceedance will appear on the UPPER CRT.
- Engine secondary Data Cue = a series of “V” in view when secondary engine data displayed on lower CRT
¡ During start, a red maximum Start EGT radial is displayed until the engine start is completed.
If this radial is reached or exceeded, EGT pointer + digital readout change to red + parameters recorded
¡ During takeoff or go-around, the EGT pointer & digital readout remain white for 5 minutes after the amber band
is reached. (but red line limits are not inhibited).
¡ N1 parameter displays a green TAI annunciation when the TAI is ON.
¡ The Limit N1 is the maximum certified thrust limit for all phases of flight and varies with existing ambient
conditions (this value is acquired from the EEC or the TMC)
With Trust Limit protection operative, Trust levers can be moved to the Forward stop Ô engines will not exceed
the displayed Limit N1.
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BOEING 767 SYSTEMS REVIEW
3. ENGINE CONTROLS
¡ Engine Fuel Control system has separate controls for starting, forward thrust and reverse thrust
¡ A lockout provision in the thrust lever assembly mechanically prevents simultaneous forward and reverse thrust.
¡ There are 2 engine Idle speeds : - Minimum idle Ô for most ground and flight operations
- Approach idle Ô higher RPM until 5" after touchdown
Ô L(R) ENG LOW IDLE advisory msg. if an engine has failed to go approach idle RPM when required
Ô IDLE DISAGREE advisory msg. if engines are at different idle settings.
¡ To command Reverse thrust deployment Forward Thrust levers must be at Idle position.
(AOM 21.20.05)
4. THRUST MANAGEMENT COMPUTER & ASSUMED TEMPERATURE TAKEOFF
¡ TMC (Thrust Management Computer) calculates a reference N1 based on existing pressure altitude & ambient
& ambient temperature data from the air data computer (ADC).
Ô Modes selected with the TMSP (Thrust Mode Select Panel)
Ô Mode displayed above the N1 indicator
Ô A/T remains in the active TMC mode even when the inner control is pulled out (but the displays are inhibited)
¡ TMC calculates the Reference N1 for Assumed temperature reduced thrust takeoff.
Ô T/O select switch cancels preselected reduced thrust
Ô Maximum reduction = 25% or selected climb thrust
Ô Climb 1 = 90% of C/T until 10000 ft
Ô Climb 2 = 80% of C/T until 10000 ft
Ô pushing CLB return TMC to FULL CLIMB
Ô Reduced Climb is automatically terminated at 12000 ft and indication disappears at 12500 ft
5. ELECTRONIC ENGINE CONTROL
¡ Each engine is controlled by a dual channel (A & B) Full Authority Digital Electronic Control (FADEC) without any
hydro-mechanical backup.
¡ Electronic Engine Control (EEC) is powered, when the engine is operating by a dedicated Permanent
Magnet Alternator (PMA) independent of aircraft electrical power.
¡ During normal EEC operation, 1 channel provides inputs to the fuel control to drive the engine to the EEC
computed thrust level. EEC always computes the limit N1 achieved at full forward thrust lever position (amber
radial on the N1 display)
¡ EEC provides N1 & N2 overspeed protection (but NO EGT protection)
¡ Both engines normally operates in an N1 control mode using channel A or channel B to control thrust.
EEC will automatically switch the channel in use on each start, or when a channel becomes incapable of N1
Control.
If EEC has no adequate inputs from the Air Data Computer (ADC), an alternate (ALTN) mode is used :
Ô L(R) ENG EEC MODE advisory msg. appears + ALTN light
Ô No more overboost protection
Ô ENG LIM PROT msg. will appear as the throttle is advanced into the overboost range
Ô L(R) ENG CONTROL & ENGINE CONTROLS advisory msg. mean that the engine control may be unreliable
and the L or R ENG RPM LIM will appear whenever N1 or N2 is at the red line limit.
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BOEING 767 SYSTEMS REVIEW
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6. ENGINE FUEL SYSTEM
¡ Fuel pressure is generated by a second stage engine driven fuel pump prior to entering the fuel / oil exchanger.
Fuel continues through a fuel filter and then metered by the EEC to meet the existing fuel requirements.
Pressurized fuel is also used to position the variable pitch stator vanes and cool the Integrated Drive Generator
(IDG) oil.
The fuel then flows through the engine fuel valve and fuel flow meter prior to the engine fuel nozzles.
¡ VALVES - SPAR valve in the main fuel tank controls the flow of fuel to the engine
- ENGINE valve (in FCU) after the EEC
Both are commanded by : - Fuel Control Switch
Engine & Spar valve lights illuminate
- Engine Fire Switch
momentarily as the valves open or close.
May remain illuminated if the valves do not
correspond to the adequate position.
¡ FCU operates in conjunction with the EEC
¡ Fuel flow is measured after the FCU & transmitted to the FMC (then used with other fuel quantities)
¡ The Fuel Filter has bypass capabilities Ô when clogged by contaminants, fuel will bypass the filter and will enter
into the FCU Ô L(R) ENG FUEL FILT advisory or status msg. Ô Erratic engine operation or flameout may occur
7. ENGINE START
¡ Air from the pneumatic duct is used to power the air driven starter.
¡ 2 igniters and NO time limit in CONT position
¡ Ignition selector :
Ô SINGLE = start on GND (EEC auto alternates the 2 igniters at each start)
Ô BOTH = start in FLT
¡ Start selector :
Ô AUTO: selected igniter(s) operate continuously when :
- Flaps are out of zero
- Engine anti-ice ON
Ô CONT: selected igniter(s) operate continuously and engine operates at minimum approach idle
Ô FLT: both igniters operate when N2 drops below idle speed (AUTO RELIGHT feature)
¡ Starting sequence :
1) Start selector to GND position Ô opens the start valve
2) Engine bleed air valve closes if opened
3) Fuel ON at Max Motoring* Ô GE……20% N2, minimum 15%
Ô PW……25% N2, minimum bug
*Max Motoring = Acceleration is less than 1% in 5 seconds.
4) LIGHT UP within 25" of fuel ON
5) 50% N2: Ô starter auto cutout. Start selector to AUTO
Ô CRT blanks momentarily at generator connection
Ô START valve closes, Ignition OFF, Bleed valve OPEN
6) N2 stabilizes within 120"
A Failure of the start valve to open = ENG START light + L(R) ENG STARTER EICAS msg.
A No starter cut out = STARTER CUTOUT on EICAS
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¡ EGT start limit
BOEING 767 SYSTEMS REVIEW
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Ô indicator displays the RED MAX START EGT until stabilized
Ô EGT pointer changes : - AMBER in caution band
- RED at red radia
A remains white for 5 min. if in caution range during T/O or G/A
¡ T/O limit is also used as limit in flight when LOSS OF BOTH ENGINES
¡ Inflight start envelope :
Ô Displayed on UPPER CRT (the highest FL is the max.) in case of engine shutdown in flight
Ô XBLD annunciated in magenta on N2 gage if cross bleed required
Ô FUEL ON command bug appears also on N2
¡ Starter cycle (depends on powerplant model, i.e. GE or PW) :
GE (Normal Duty Cycle)
1 min ON
.… 1 min OFF
… INDEFINITELY
GE (Extended Duty Cycle)
2 min ON ..… 1 min OFF … INDEFINITELY
5 min ON ..… 2 min 30 sec OFF …. 5 min ON
.…10 min OFF … INDEFINITELY
PW (Normal Duty Cycle)
2 consecutive aborted starts with EGT cooling periods. After second cooling period, let N2 drop to 0 before reengagement.
PW (Heavy Duty Cycle)
5 min ON
…
N2 = 0
… INDEFINITELY
10 min ON … 10 min OFF … INDEFINITELY
15 min ON … 15 min OFF … INDEFINITELY
¡ Starter reengagement (GE) :
Ô 0% N2 = recommended
Ô 0-20% = Normal
Ô 30% = Permissible for fuel purging or clear a fire
Ô above 30% = may result in starter damage
¡ Starter reengagement (PW) :
Ô No re-engagement > 20 % N2
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BOEING 767 SYSTEMS REVIEW
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8. OIL SYSTEM
¡ Quantity in litres displayed on the EICAS.
¡ Oil sequence :
1) Oil system is pressurized by an oil pump driven by the N2 rotor (press. is sensed after the filter)
2) Oil passes through an oil filter (if filter is contaminated oil will bypass it).
3) Oil goes to the engine for lubrication & cooling then returns to a scavenge pump (also driven by N2 rotor)
4) Temperature is sensed after it leaves the scavenge pump
5) Oil passes through a fuel/oil heat exchanger where it is cooled
6) Oil flows to another bypass filter before returning to the oil tank
A Oil press. below 10 PSI = LOW PRESSURE light
A Filter bypass = L (R) OIL FILTER msg.
9. THRUST REVERSER
¡ (GE only) Powered by its respective engine bleed air (PNEUMATIC POWER)
Ô Loss of L (R) engine bleed air = respective reverser inoperative
¡ "REV" amber = unlocked or in transit / "REV" green = interlock released / fully deployed
¡
Pulling UP the reverse levers: - disengage autothrottle
- deploys speedbrakes if in DOWN position
¡ "REV ISLN VALVE" on EICAS and "REV ISLN" are ON when a fault is detected in the system.
In flight, the light and message are inhibited until after landing.
¡ Thrust lever can be deployed only on ground when the forward thrust lever is at idle position
Electro-mechanical lock prevents uncommanded reverser deployment in the event of additional system failure.
If uncommanded reverser movement is sensed, the isolation valve opens automatically & pneumatic pressure
Is applied to stow the reverser = AUTOSTOW feature.
10. VIBRATION SYSTEM
¡ 2 engine mounted accelerometers that sense engine vibrations Ô Tracking filter to isolate FAN, N2 and LPT
The component with the highest vibration is identified & the highest vibration value is displayed on the EICAS
FAN……..Low pressure compressor
LPT……………Low pressure turbine
N2………High pressure compressor
BB……Broad Band engine vibration
¡ Filter failure = vibration displayed as Broad Band (BB)
11. FAULTS
CENTER PANEL
L ENG
(amber) :
OIL PRESS
- Respective engine oil pressure is at or below minimum limit (10 PSI)
or
- Oil pressure switch malfunction
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BOEING 767 SYSTEMS REVIEW
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CONTROL STAND
REV
ISLN
(amber) : Ground only - indicates a fault has been detected in the thrust reverser system.
CONTROL STAND
ENG
VALVE
(amber) : Engine fuel valve in fuel control unit is not in commanded position.
SPAR
VALVE
(amber) : Fuel spar valve at the front spar is not in commanded position
OVHD PANEL
NORM
ALTN
- NORM : Electronic Engine Control (EEC) Mode switch in normal position
- blank : alternate EEC mode selected
(amber) : EEC operating in alternate mode.
OVHD PANEL
L/R
VALVE
(amber) :
- Valve is not in signaled position
or
- N2 exceeds approximately 50% and start valve still open (i.e. no starter cutout)
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BOEING 767 SYSTEMS REVIEW
POWERPLANT
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BOEING 767 SYSTEMS REVIEW
ENGINE START SCHEMATIC
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BOEING 767 SYSTEMS REVIEW
Engine Electronic Control (EEC)
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BOEING 767 SYSTEMS REVIEW
ENGINE OIL SYSTEM
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BOEING 767 SYSTEMS REVIEW
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BOEING 767 SYSTEMS REVIEW
ENGINE FUEL SYSTEM
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BOEING 767 SYSTEMS REVIEW
ENGINE REVERSER SYSTEM
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BOEING 767 SYSTEMS REVIEW
ENGINE REVERSE LOGIC
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BOEING 767 SYSTEMS REVIEW
ENGINE FIRE DETECTION
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