maintenance management 2

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Maintenance management By m.shahbazi 4/18/2011

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In the name of GOD

Part 1

Maintenance Management

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Maintenance Management




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Maintenance:

1. means any one or combination of overhaul, repair,

inspection, replacement, modification or defect

rectification of an aircraft or component, with the

exception of pre-flight inspection;(EASA definition)

pre-flight inspection: means the inspection carried out

before flight to ensure that the aircraft is fit for the

intended flight.

Def in i t ion

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Maintenance:

2. Means the performance of tasks required to ensure the

continuing airworthiness of an aircraft, including any

one or combination of overhaul, inspection,

replacement, defect rectification, and the embodiment of

a modification or repair.(ICAO-Annex 6/8)

3. Means the set of action including inspection, servicing,

and determination of condition required to achieve a

derived outcome which restore an A/C part and

equipment in serviceable condition.

Def in i t ion




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Repair:

The restoration of an aeronautical product to an airworthy

condition as defined by the appropriate airworthiness

requirements.

Maintenance Management:

Administrative, financial, and technical framework forassessing and planning maintenance operations on a

scheduled basis.

Def in i t ion

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MPD : Maintenance Planning Data Document

is the basis for the initial recommended maintenance

programme for newly certified aircraft;

continuing airworthiness maintenance information sometimes

issued as a maintenance planning document.

Def in i t ion




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Maintenance programme:

A document which describes the specific scheduled

maintenance tasks and their frequency of completion and

related procedures, such as a reliability programme,

necessary for the safe operation of those aircraft to which

it applies.

Def in i t ion

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Cert i f i c at ion Maintenanc e Requi rement

(CMR) :

Maintenance that is required by design to help show

compliance with the appropriate type certification

requirements by detecting the presence of, and therebylimiting the exposure time to, a significant latent failure.

Where the maintenance tasks result from a system safety

analysis, they are usually known as CMRs.

Latent failure : A failure that is not detected and/or

enunciated when it occurs.

Def in i t ion




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(CMR) :

Maintenance that is required by design to help show

compliance with the appropriate type certification

requirements by detecting the presence of, and thereby

limiting the exposure time to, a significant latent failure.

Where the maintenance tasks result from a system safety

analysis, they are usually known as CMRs.

Latent failure : A failure that is not detected and/or

enunciated when it occurs.

Def in i t ion

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(CMR) :

It should be noted that some CMRs require the

performance of certain flight crew procedures. When

included in a CMR, these procedures are mandatory

and should be shown as such in the flight manual or

equivalent document.

It is likely that future design developments will limit the

use of CMR to maintenance tasks

Def in i t ion




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(CMR) :

For aircraft with aeroplane maintenance manuals

formatted in accordance with Air Transport Association of

America Specification 2200 (ATA 2200), formerly

Specification 100 (ATA-100), CMRs can be included

in Chapter 5 but are sometimes contained in the

appropriate section of the ATA 100 maintenance planningdata document (MPD) or in a separate airworthiness

limitations manual.

Def in i t ion

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Airworthiness Limitations :

structural life limits associated with fatigue

requirements for structures. ( specially for helicopter)

Def in i t ion




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Instructions for continued airworthiness (ICA):

Instructions for continued airworthiness (ICA) are

developed by the design approval holder and some of

these instructions are approved by the State of Design

They provide guidance to the operator about what is

necessary to maintain the airworthiness of the aircraft,

engine, or propeller, including incorporated

modifications or repairs, over time.

They provide documentation of necessary methods,

inspections, processes, and procedures

Def in i t ion

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These instructions are distributed in two categories

depending on the compliance requirements:

1. maintenance requirements that have been specified

as mandatory in the approval of the type design and,

2. those for which compliance is recommended

Def in i t ion




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The ICA may include sections on airworthiness

limitations, certification maintenance requirements

(CMR), maintenance instructions, engine and, if

applicable, propeller maintenance, component

maintenance, system wiring diagrams, and non-destructive

test and inspection. A cross-check should be conducted

to ensure that ICA elements required by the relevant

airworthiness code are addressed in the aircraft

documentation.

Def in i t ion

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Availability

Availability is a measure of the degree to which an item is

in an operable state and can be committed at the start of a

mission when the mission is called for at an unknown

(random) point in time. Availability as measured by the

user is a function of how often failures occur andcorrective maintenance is required, how often preventative

maintenance is performed, how quickly indicated failures

can be isolated and repaired, how quickly preventive

maintenance tasks can be performed, and how long

logistics support delays contribute to down time.

Def in i t ion




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Maintainability

Maintainability is the ability of an item to be retained in,

or restored to, a specified condition when maintenance is

performed by personnel having specified skill levels, using

prescribed procedures and resources, at each prescribed

level of maintenance and repair.

Def in i t ion

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Reliability

The probability that an item will perform its intended

function without failure under stated conditions for

specified period of time.

Reliability is divided into:

1. mission reliability and

2. logistics reliability.

Def in i t ion




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Maintenance release.

A document which contains a certification confirming that

the maintenance work to which it relates has been

completed in a satisfactory manner, either in accordance

with the approved data and the procedures described in the

maintenance organization’s procedures manual or under

an equivalent system.(CRS=Certificate of Release to

Service)

Def in i t ion

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1. Reactive maintenance

2. Preventive maintenance

3. Predictive maintenance

4. Total productive maintenance

5. Reliability-centered maintenance

Type o f ma in t enance




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1. Reactive Maintenance( corrective maintenance)

Is any maintenance activity which is required to correct a

failure that has occurred or is the process of occurring.

Reactive maintenance involves all unscheduled actions performed

as a result of system or product failure. Basically, it is an attempt

to restore the system/product to a specified condition.


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1. Reactive Maintenance:

Reactive Maintenance consist of

1. failure identification,

2. localization and isolation,3. disassembly,

4. item removal and replacement or repair in place,

5. reassembly, and

6. checkout and condition verification





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Is maintenance, including tests, measurement,

adjustment, and parts replacement, performed

specifically to prevent faults from occurring.

the prevention of equipment breakdowns before they

happen.


Periodic maintenance

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Typical preventive maintenance activities include:

1. periodic inspections( schedule maintenance),

2. critical item replacements, and

3. servicing and cleaning, and

4. calibrations.





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Periodic maintenance (TBM)

Time Based Maintenance (TBM) or scheduled

maintenance consist of periodically inspection,

servicing and cleaning equipment and replacing partsto prevent sudden failure and process problems.


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benefits of preventive maintenance :

1. Safety,

2. Lower cost,3. Reduction in failures and breakdowns,

4. Extension of equipment life,

5. Increased equipment reliability,

6. Fewer surprises,

7. Reduced overall maintenance

8. Etc.





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3. Predictive maintenance (CBM)

Condition Based Maintenance (CBM) is a method in

which the service life of important part is predicted based

on inspection or diagnosis, in order to use the parts to the

limit of their service life.


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Total Productive Maintenance (TPM) is preventive

maintenance plus continuing efforts to adapt, modify, and

refine equipment to increase flexibility, reduce materialhandling, and promote continuous flows.

It is operator-oriented maintenance with the

involvement of all qualified employees in all

maintenance activities.

Developed in Japan, TPM places a high value on teamwork,

consensus building, and continuous improvement.





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TPM means total employee involvement, total equipment

effectiveness, and a total maintenance delivery system. In

order to achieve this, machine operators must share the

preventive maintenance efforts, assist mechanics with

repairs when equipment is down, and work on equipment

and process improvements within team activities.

Methodology designed to ensure that every machine in a

production process always performs its required task and

its output rate is never disrupted


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TPM has been described as preventive maintenance with

these three factors added:

1. involving machine operators in preliminary

maintenance activities by encouraging them to keep

machines clean and well lubricated;

2. encouraging operators to report indications of

incipient distress to the maintenance department; and

3. establishing a maintenance education and training

program.





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5S for TPM




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It has been assumed that preventive maintenance

programs help to ensure reliability and safety of

equipment and machinery. However, tests performed by

airlines in the mid-1960s showed that scheduled overhaul

of complex equipment had little or no positive effect on

the reliability of the equipment in service.

These tests revealed the need for a new concept of preventive maintenance, which later became known as

reliability-centered maintenance (RCM).


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the RCM process can be considered as three separate but

associated analyses:

1. failure mode and effects analysis,

2. consequence analysis, and

3. task analysis.

These analyses consider the specific characteristics and

consequences of a failure and attempt to arrive at the

optimal solution based on this information.





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Phase I (unto 1958)

Hard-Time maintenance concept (HT) :

Failures caused by wear out.

Discard or full overhaul of all aircraft parts at specified

interval.

Disadvantage:

High maintenance cost.

Low availability of aircraft.

Ai rc ra f t m a in tenanc e his to ry

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Phase II (1958-1968)

Draw-backs of hard time concept unacceptable.

On condition maintenance (OC) :

Periodic inspections or Checks to verify system orcomponent function against prescribed standards.

Reliability programs:

Determine optimal overhaul/inspection or test life .

Keep Failure rate below a predetermined level.





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On Condition:

Repetitive inspections, or tests to determine the condition

of units or systems or portions of structure maintenance

This is also a preventive primary maintenance process that

requires a system, component, or appliance be inspected

periodically or checked against some appropriate physical

standard to determine if it can continue in service.

The standard ensures that the unit is removed from service

before failure during normal operation. These standards

may be adjusted based on operating experience or tests, as

appropriate, in accordance with a carrier’s approved

reliability program or maintenance manual.


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Phase III (1968-1980)

Start with the development of the jet airliners in late 1960s.

Maintenance Steering Group (MSG)-ATA taskforce :

Condition Monitoring (CM):

Failure rate for components with a random failure

behavior can not be control by schedule maintenance .

Do not assign scheduled maintenance for such component

but control reliability .





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Phase III (1968-1980)


from the continuing analysis of the reliability program

results some surprising conclusions were drawn.

It appeared that there is a category of system and

powerplant components for which the failure rate could

not be influenced by whatever amount of hart-time or on-

condition maintenance.

These components had a random failure behavior on

which maintenance has no effect. even deleting schedule

maintenance would therefore not affect reliability of

component, system and aircraft.


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Phase III (1968-1980)


This lead to the introduction of the Condition Monitoring.

This philosophy was first in the development of the

maintenance program for the boeing 747 aircraft. A joint airline/manufacturer taskforce called Maintenance

String Group (MSG) developed a decision logic to

initially determine which of the 3 processes was

applicable to a certain system or component.

HT or OC or CM ?





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Condition Monitoring:

This is a primary non-preventative maintenance process. Items

classified in this process are permitted to fly-to-failure without

a plan for removal. Therefore,

safety related items are not eligible for condition monitoring

classification. Items classified in the condition monitoring

process do not have an adverse relationship between age and

reliability. For items that have neither hard time limits nor on

condition maintenance as their primary maintenance process.Condition monitoring is accomplished by appropriate means

available to an operator for finding and resolving problem

areas. These means range from notices of unusual problems to

special analysis of unit performance


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Phase III (1968-1980)

To extend the hard time intervals a lot of reliability

analyses were performed

These data present 6 basic patterns for Age-Reliabilityrelationship.

From the 6 curve can be concluded that 11% (1,3,5)

might benefit from a limit on operating Age.

89% cannot benefit from such a limit.





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4%

5%

2%

7%

14%

68%

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Phase III (1968-1980)

MSG-1 Document-1968

Analyses system for B-747 MP.

MSG-2 Document-1970 Not aircraft type related

Component level (bottom-up approach)

Maintenance process oriented





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Phase IV (1980)

MSG-3 Document-1980

System level (top-down approach).

Maintenance task oriented.

MSG-3 Revisions


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Note:

units may be subject to control by two or even all three of

the primary processes.

The basic engine has characteristics that involve all three

primary maintenance processes

Programs that control engine major overhaul intervals

consider the engine as a hard-time unit.

Programs controlling shop maintenance to a

"conditional“ standard (restoration, etc.,) may classify

the engine as on-condition or as condition-monitoring

depending on the characteristics of the program





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MSG-1:

The decision logic and analysis procedures were

contained in a document entitled

“Airline/Manufacturer Maintenance Program Plan

Document” refer to as MSG-1.

These procedures were used by the aviation industry and

the State of Design’s regulatory authority to develop

initial minimum maintenance recommendations for the

B-747 aeroplanes.

MSG-1,2,3

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MSG-2:

Through experience gained from this logic, procedures

were updated to produce a universal document which

could be applied to future newly certificated

aeroplanes. This effort resulted in the MSG-2 document.

The MSG-2 logic was used to develop initial minimum

maintenance procedures during the 1970s.

MSG-1,2,3




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MSG-3:

In 1980, with the combined efforts of aeroplane and

engine manufacturers, airlines, aviation interest groups

and regulatory authorities worldwide, new decision

logic and analysis procedures were generated in a

document called MSG-3 .

Then, in light of the experience gained in using MSG-3

analysis on a number of aeroplanes, industry issued

several revisions to MSG-3

MSG-1,2,3

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MSG-3R1:

In 1987, the airline industry decided that the benefits of

the experience gained from using MSG-3 should be used

to improve the document for future applications. This

document revised the “Inspection” definitions andremoved “Operating Crew Monitoring” tasks, as well as

limiting what was then considered to be “Normal Duties”

for flight crew.

MSG-1,2,3




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MSG-3R2:

In 1993, Revision 2 was incorporated. It included; a

requirement for a Corrosion Prevention and Control

Program (CPCP), more revised inspection definitions,

new procedures to ensure tasks and intervals reflected an

aircraft’s type certificated operating capabilities and tasks,

to ensure compliance with Type Certification

requirements.

MSG-1,2,3

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MSG-3 R2001.1. In 2001 MSG was revised. The revision

again changed inspection definitions, e.g.: it limited the

distance and added the use of a mirror to the “General

Visual Inspection”, incorporated new guidance on

operating crew “normal duties” when determining if a

functional failure is evident, expanded wording on hiddenfunctions of safety/emergency equipment, and

incorporated “enhanced zonal analysis”. It also

incorporated analysis for Lightning and High Intensity

Radiated Fields (L/HIRF), and added new terms to the

glossary to bring the document into closer alignment with

reliability centred maintenance criteria.

MSG-1,2,3




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MSG-3 R2002.1.

In 2002, MSG was revised. It emphasized the importance

of recording any and all assumptions made during

analysis, added a procedure for Fault-Tolerant analysis,

added an explanation on the use of the MMEL when

answering system analysis level 1, question 4, clarified the

definition of General Visual Inspection (GVI), and added

a glossary.

MSG-3 R2003.1.

In 2003, MSG was again amended to clarify processes

with respect to Fault Tolerant Systems.

MSG-1,2,3

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the maintenance review board (MRB) process used during

the development of an initial scheduled maintenance

programme,

usually done for derivative or newly certificated large

aeroplanes as appropriate.

The primary purpose of the MRB process is to assist

the design organization and the operator in

establishing an initial approved maintenance

programme for aeroplanes and the regulatory authority

in approving that programme.

MRB




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Working groups (WGs).

1. One or more WGs, consisting of specialists from

participating operators, design organizations and

regulatory authorities, may also be formed to

develop initial minimum maintenance

requirements for new or derivative aeroplanes.

The ISC ensures that applicable supporting

technical data and analysis are provided to the WG.

MRB

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The MRB Report becomes the basis for the first issue of

an operator’s initial maintenance programme.

Adjustments may be necessary to address

operational or environmental conditions unique to that

operator.

Through operator experience, and with regulatoryapproval, additional changes to the maintenance

programme may be made by the operator in order

to maintain a safe and efficient maintenance

programme.

MRB Repo rt



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