393SYS
Airport Engineering Practice
Lecture 3
Development of
Maintenance
Programs
1
2.0 Development of Maintenance Programs
Summary of Last Lecture
Systems, Subsystems and Components
Reliability Parameters
Development of Maintenance Programmes
The Process Oriented Approach

Hard Time

On Condition

Condition Monitoring

The Maintenance Steering Group Approach (MSG-2)

Process Oriented Maintenance
o
The Hard Time Process
o
The On Condition Process
o
The Condition Monitoring Process
2
2.0 Development of Maintenance Programs
Task Oriented Maintenance
These procedures are referred to as MSG-3.
MSG-3 is a modification of and an improvement on the
MSG-2 approach.
MSG-2 was a bottom-up approach – involves monitoring
systems at their component level to detect failure
conditions.
MSG-3 is a “top-down” approach which is used to identify
suitable scheduled maintenance tasks to prevent failures
and maintain the reliability of the system.
3
2.0 Development of Maintenance Programs
MSG-3 asks - how does a particular failure affect the
operation of the aircraft ?
It does not matter whether a system, subsystem, or
component fails.
What matters is how the failure affects the aircraft
operation.
Failures are assigned one of two basic categories –
 Safety, or
 Economic
The following diagram is a simplified version of the first
step in the MSG-3 logic process :
4
(1)
Is the Failure
Evident to the
Operating Crew ?
Yes
No
(2)
Does Failure Affect
Operating Safety ?
No
(3)
Does Hidden
Failure +
Related System
Failure Affect
Operating
Safety ?
(4)
Does Failure
Affect Operating
Capability ?
Yes
Yes
(5)
Safety
No
No
Yes
(6)
(7)
(8)
(9)
Operational
Economic
Non-Operational
Economic
Safety
Non-Safety
Economic
Evident Failures – (A)
Hidden Failures – (B)
5
2.0 Development of Maintenance Programs
The flow chart in this figure is used to determine if
the failure is evident to the flight crew or hidden
from them.
Once this is determined another set of flow charts is
used to determine what type of maintenance is
performed – see pages 26 and 27 of the course text
book by Kinnison.
The decision logic built into these flow charts is used
to identify suitable scheduled maintenance tasks to
prevent failures in aircraft systems, and to maintain
the inherent level of reliability of the system.
6
2.0 Development of Maintenance Programs
There are three categories of tasks
developed by the MSG-3 approach :
(a) airframe systems tasks
(b) structural item tasks
(c) zonal tasks
7
2.0 Development of Maintenance Programs
A. Maintenance Tasks for Airframe Systems
Decision analysis results obtained using MSG-3 assigns a combination of the
following eight tasks –
1. Lubrication – applying oil and grease to reduce friction and wear.
2. Servicing – attending to basic needs of components and/or systems.
3. Inspection – Examination of an item and comparison against a standard.
4. Functional Check – Measurements are made to determine if each function of an
item performs within specified limits.
5. Operational Check – Determines if an item is fulfilling it’s intended purpose.
Does not require measurements of tolerances.
6. Visual Check – Observation used to determine is fulfilling its intended purpose.
Does not require measurements of tolerances.
7. Restoration – Returns an item to a specified standard. Varies from simple cleaning
to complete overhaul.
8. Discard – Removes an item from service at a specified life limit.
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2.0 Development of Maintenance Programs
B. Maintenace Tasks for Structural Items
Airplanes are subjected to three sources of structural deterioration –
1. Environmental Deterioration: Deterioration of an item’s strength or
resistance to failure as a result of interaction with climate or the
environment.
2. Acidental Damage : Deterioration of an item caused by –
 impact with some object which is not part of the airplane,
 errors in manufacturing
 damage during operation
 damage during maintenance
3. Fatigue Damage : The formation of cracks due to cyclic loading.
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2.0 Development of Maintenance Programs
Failure of structural components due, for example, to metal fatigue.
10
2.0 Development of Maintenance Programs
These different forms of structural deterioration can only be
detected by inspection.
The inspections must be made at three different levels of
detail :
1. General visual inspection : This requires the opening or
removal of access doors or panels. Work stands or ladders
may be required to access some of the components.
2. Detailed inspection : an intensive visual inspection which
looks for irregularities using mirrors, magnifying glasses,
etc.
3. Special detailed inspection : This type of examination typically
requires high-powered magnification, ultrasonics detection, penetrating
dyes, magnetic particles, eddy currents, etc (see Chapter 18 of course
text book for details on these methods).
11
2.0 Development of Maintenance Programs
C. Zonal Maintenance
The zonal maintenance program ensures that all systems,
components, and installations contained within a specific
zone on the vehicle receive adequate attention.
The program takes a number of general visual inspection
tasks from the maintenance program of various systems, and
then applies them to systems in one or more zones.
A zone overlaps
several systems
Each coloured rectangle
represents a different
system.
12
In this diagram, the
zone is a wing and
includes all the
systems which are
built into this wing.
13
3.0
Aviation Industry
Certification
Requirements
14
3.0 Aviation Industry Certification Requirements
Aircraft Certification
The aviation industry is the most heavily regulated of
all the different forms of transport.
There are three certificates necessary for full
certification of an airplane :
1.
The Type Certificate – certifies the aircraft
design.
2.
The Production Certificate – certifies the
manufacturing process.
3.
The Airworthiness Certificate – certifies the
aircraft itself.
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3.0 Aviation Industry Certification Requirements
Type Certificate
•
Each aircraft designed and built for commercial as
well as private use must have an approved type
certificate (TC).
•
This certificate is applied for by the designers of the
vehicle once the basic design has been determined.
•
The TC defines the vehicle airframe, its engines, and
the various instruments, systems and other
equipment.
•
If more than one engine type is available for the aircraft,
the TC must cover all of them.
•
The TC also defines the capabilities and limitations
of the aircraft …
16
3.0 Aviation Industry Certification Requirements

Passenger carrying limits.

Cargo carrying limits.

Altitude limits.

Fuel capacity.

Top speed.

Cruising speed.
All of these parameters must be identified on a data sheet
attached to the certificate.
The design of an aircraft must be proven to meet aviation
authority standards by means of inspections and test
flights.
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3.0 Aviation Industry Certification Requirements
The TC is applied for early in the design stage but it
is not awarded until the aircraft is –

actually built,

tested in flight, and

proven to meet the required standards of
safety and airworthiness.
For example, the Boeing company applied for the
TC for the 757-200 aircraft in 1978 but it was not
awarded until 1982.
A sample TC is shown in the next slide.
18
1.
Type certificate
number.
2.
Applicant’s name.
3.
Applicable
regulation.
4.
Product type
designation. e.g.:
“Airplane Model
787”.
5.
Date of original
application.
6.
Date TC is issued.
7.
Signature of
manager of
issuing authority.19
3.0 Aviation Industry Certification Requirements
Production Certificate
Once the type certificate is awarded, the manufacturer must
apply for a Production Certificate (PC).
The PC is awarded when the appropriate aviation authority is
satisfied that the manufacturer has –

the necessary manufacturing facilities

established an effective quality control programme to
ensure that each aircraft they produce will be built to
the TC standards.
The aircraft manufacturer usually gets one PC and each aircraft
they produce will be added to that original PC by the
appropriate aviation authority.
The sample on the following slide shows the first page of a
typical PC.
20
3.0 Aviation Industry Certification Requirements
Note : A PC may be
cancelled, suspended,
superceded or revoked for a
just cause at any time !
21
3.0 Aviation Industry Certification Requirements
Airworthiness Certificate
The third certificate – the airworthiness certficate (AC) –
confirms that the aircraft –

has been inspected

conforms with its type certificate,and

is in airworthy condition.
The airworthiness certificate is applied for by the manufacturer.
It is awarded –

after the aircraft has passed all inspections, and

after the aircarft has passed a successful flight test, and

when the aircraft “rolls out the door” – just prior to
delivery to a customer.
22
3.0 Aviation Industry Certification Requirements
Airworthiness Certificate
The AC contains the aircraft’s unique serial (tail) number.
The AC remains valid as long as -
a)
the aircraft meets its type design
b)
the aircraft is in a condition safe for operation
c)
all airworthiness directives have been complied with,
and
d)
maintenance and alterations are performed in
accordance with the relevant aviation authority rules.
A typical airworthiness certificate is shown on the next slide.
Is is required that this certificate be prominantly displayed in
aircraft.
In passenger aircraft it is usually posted by the main entry
door.
the
23
3.0 Aviation Industry Certification Requirements
Note : An AC may be cancelled, suspended, superceded or revoked if any
24
of the conditions on the previous slide are not met !
3.0 Aviation Industry Certification Requirements
Operator’s Certificate (OC)
An operator cannot just buy an aircraft and enter into commercial
service.
In the USA, the operator must meet the requirements of –

the Department of Commerce with regard to the business
aspects of the airline operation, and

the Department of Transportation with regard to the
technical aspects.
The operator has to demonstrate that they –

understand the business of commercial aviation

understand the operational and maintenance aspects of
commercial aviation, and

have the the necessary people, pacilities, and processes
in place to carry out an airline business.
25
3.0 Aviation Industry Certification Requirements
The OC, once issued by the relevent government
agency, states that –
“the airline is authorized to operate in accordance with
the relevents Acts and its rules and regulations, and the
terms, conditions, and limitations contained in the
operations specification.”
The US Federal aviation act of 1958 requires the airline
to develop and “operations specifications” document
(Ops Spec for short) for each type of aircraft to be
operaed in commercial service.
26
3.0 Aviation Industry Certification Requirements
The Ops Spec outlines such operational activities as –
a)
the type of service to be offerered – passenger, cargo or
combination,
b)
the type of aircraft to be used,
c)
the routes to be flown,
d)
the airports and alternate airports that will be used,
e)
the navigation and communications facilities to be utlized on each
route,
f)
the way points used in navigation,
g)
the take off and approach routes,
h)
the maintenance and inspection program applicable each
particular aircraft model including the scheduled and unscheduled
maintenance programs, and
i)
the quality assurance and reliability programs.
27
3.0 Aviation Industry Certification Requirements
Certification of Personnel
An airline is typically required by law to have sufficient full time
qualified management and technical personnel to ensure a high
degree of safety in its operations.
The basic personnel requirements are typically –

a Director of Safety

a Director of Operations

a Director of Maintenance

a Chief Pilot

a Chief Inspector
What ever the positions created by the airline, they must be able
to show that they can operate safely.
This means the personnel must have the necessary training,
experience and expertise.
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4.0
Documentation for
Maintenance
29
4.0 Documentation For Maintenance
Types of Documentation
It has been said that the paper documentation required for the
maintenance of a modern jet liner would weigh about the
same as the airplane itself !
Whether or not this is true, there is certainly a considerable
amount of documentation.
This section will look at two main types of documentation –
1.
Manufacturer’s Documentation
2.
Airline Generated Documentation
30
4.0 Documentation For Maintenance
Manufacturer’s Documentation
1. Airplane Maintenance Manual (AMM)
Contains all the basic information on the operation and
maintenance of the aircraft and its on-board equipment.
Explains how each system and subsystem works.
Describes basic maintenance and servicing actions such as
removal and installation of LRUs.
2 Component and Vendor Manuals
All components built by the aircraft manufacturer will be
accompanied by a component maintenance manual.
Vendor Manuals (VM) are written by the manufacturer of
components and systems built by outside vendors.
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4.0 Documentation For Maintenance
3. Fault Isolation Manual (FIM)
Contains a set of fault isolation trees for locating and fixing
various systems and components on aircraft.
Example
for a car
engine.
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4.0 Documentation For Maintenance
3. Fault Reporting Manual (FRM)
Designed to be used by the flight crew – e.g. where to begin
looking in the FIM for the source of a problem
The flight crew identifies their problem using a series of
questions and diagrams of system operation and instrument
indications.
This leads to an 8-digit code which is reported to the ground
station.
Maintenance people then use this code to find the appropriate
solution.
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4.0 Documentation For Maintenance
4. Illustrated Parts Catalogue (IPC)
Includes lists and location diagrams of all parts used on an
aircraft.
Includes information on part numbers, vendors, and
interchangeability.
5.
Storage and Recovery Document (SRD)
Contains information for maintenance and servicing of
aircraft that are to be out of service and stored for long periods
of time.
Includes procedures for draining certain fluids, moving the
aircarft so that the tires will not go flat, and protecting
components from the weather.
34
4.0 Documentation For Maintenance
6. Structural Repair Manual (SRM)
Provides the airline operator with information for performing
simple structural repairs.
More complex repairs require the specialized facilities of the
airframe manufacturer.
7. Maintenance Planning Data Document (MPD)
Provides the airline operator with a list of maintenance and
servicing tasks to be performed on the aircraft.
Some of these tasks were developed by the MSG process.
35
4.0 Documentation For Maintenance
8. Schematic Diagram Manual (SDM)
This document contains the detailed schematic diagrams of

electrical,

electronic, and

hydraulic systems
… on the aircraft.
The AMM (see earlier slide) contain only simplified diagrams
to aid in troubleshooting.
36
Examples of schematic diagrams.
See also http://www.b737.org.uk/
37
4.0 Documentation For Maintenance
9. Wiring Diagram Manual (WDM)
This shows the complete run of all wiring on an aircraft
including –
►
cable bundle numbers and routing,
►
plug and connector numbers and locations,
►
bulkheads, and other structural elements through which
the wiring is routed.
10. Master Minimum Equipment List (MMEL)
A list of equipment identified by the manufacturer which may
be degraded or inoperative while the aircraft is in operation …
… providing the system is fixed within the prescribed time
limit set by the MMEL.
38
Summary
Summary
Task Oriented Maintenance

MSG-3 and MSG-2

A simplified MSG-3 Logic Diagram

Maintenance Tasks for Airframe Systems

Maintenance Tasks for Structural Items

Zonal Maintenance
Aircraft Certification Requirements
Documentation For Maintenance

Manufacturer’s Documentation
39
What you need to know for the exam !

Can you briefly describe the main characteristics of the MSG-3
approach to maintenance and how it differs from MSG-2 ?

Given the simplified logic diagram for MSG-3, could you trace a
particular sequence of questions and arrive at a particular result ?

Could you identify or briefly describe some or all of the
maintenance tasks identified in the three categories of tasks
developed by the MSG-3 approach ?

Given a simple schematic diagram of a commercial aircraft,
could you explain what zonal maintenance refers to ?

If you were given a sample of one of the main certifications
required for commercial aircraft, could you identify the main
items of information they must include ?

Can you identify and briefly describe 5 different types of
maintenance documentation provided by aircraft manufacturers 40?