393SYS Airport Engineering Practice Lecture 3 Development of Maintenance Programs

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393SYS 393SYS Airport Engineering Airport Engineering

PracticePractice

Lecture 3Lecture 3Development of Development of

MaintenanceMaintenanceProgramsPrograms

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Summary of Last Lecture

Systems, Subsystems and Components

Reliability Parameters

Development of Maintenance ProgrammesThe Process Oriented Approach Hard Time On Condition Condition Monitoring The Maintenance Steering Group Approach (MSG-2)

Process Oriented Maintenanceo The Hard Time Process

o The On Condition Process

o The Condition Monitoring Process

2.0 Development of Maintenance Programs

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2.0 Development of Maintenance ProgramsTask 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.

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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 :

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Is the Failure Evident to the

Operating Crew ?

(1)

No

Does Failure Affect Operating

Safety ?

(2)

Does Hidden Failure +

Related System Failure Affect

Operating Safety ?

(3)

Does Failure Affect Operating

Capability ?

(4)

Yes

YesYes

No

No

(5)

Safety

(6)

Operational Economic

Yes No

(7)

Non-Operational Economic

(8)

Safety

(9)

Non-Safety Economic

Evident Failures – (A) Hidden Failures – (B)

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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.

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There are three categories of tasks developed by the MSG-3 approach :

(a) airframe systems tasks

(b) structural item tasks

(c) zonal tasks

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2.0 Development of Maintenance ProgramsA. Maintenance Tasks for Airframe SystemsDecision 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 ProgramsB. Maintenace Tasks for Structural ItemsAirplanes 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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Failure of structural components due, for example, to metal fatigue.

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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).

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2.0 Development of Maintenance ProgramsC. 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.

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In this diagram, the zone is a wing and includes all the systems which are built into this wing.

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3.0

Aviation Industry Certification

Requirements

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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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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 …

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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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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.

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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.

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3.0 Aviation Industry Certification RequirementsProduction 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.

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Note : A PC may be cancelled, suspended, superceded or revoked for a just cause at any time !

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3.0 Aviation Industry Certification RequirementsAirworthiness 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.

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3.0 Aviation Industry Certification RequirementsAirworthiness 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 the aircraft.

In passenger aircraft it is usually posted by the main entry door.

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Note : An AC may be cancelled, suspended, superceded or revoked if any of the conditions on the previous slide are not met !

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3.0 Aviation Industry Certification RequirementsOperator’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.

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3.0 Aviation Industry Certification RequirementsThe 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.

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3.0 Aviation Industry Certification RequirementsThe 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.

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3.0 Aviation Industry Certification RequirementsCertification 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

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4.0 Documentation For Maintenance

Types of DocumentationIt 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

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Manufacturer’s Documentation1. 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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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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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. 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.

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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.

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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.

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Examples of schematic diagrams.

See also http://www.b737.org.uk/

http://www.b737.org.uk/

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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.

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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

Summary

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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 ?

Documents

393SYS Airport Engineering Practice Lecture 3 Development of Maintenance Programs