JAP 100A 01 Chap 5.3.1-UNCONTROLLED COPY WHEN PRINTED-Lifing of Aerospace Components

Most failures of aerosystem components occur in 4an unpredictable 3manner that is not related to usage; such failures can only be dealt with by replacing components as and when they become unserviceable. There are, however, some components, usually mechanical ones, for which the probability of failure increases with age and usage. Two groups of such components justify replacement or removal for maintenance on a predetermined basis. They are:

1 Components for which airworthiness and safety considerations require that in-use failure should be minimized or eliminated.

2 Components for which the timely replacement or removal for maintenance would significantly increase system availability or decrease overall costs.

Components that belong to either or both groups are subject to the lifing procedures described in this chapter.

1.2 Associated publications

This chapter is associated with the following publications:

1 JSP 482 – Ministry of Defence Explosives Regulations.

2 JAP 100A-01 Chapter 13.5 – Compressed Gas Cylinders Having an Airborne Application.

3 Acquisition Operating Framework

4 DAP 108A-0006-2(N/A/R)1 – 4Survival Equipment and Aircrew Equipment Assemblies.3

1.3 Applicability

This chapter defines the lifing policy for all aerosystem components used in the Military Air Environment, with the exception of:

1 Aero-engines, modules and accessories, whose lifing policy is published in AP 100E-01B 4or other platform specific publication3.

2 Explosives and aerospace components that contain explosives or ancillaries (eg suspension lugs), whose lifing policy is contained in Chapter 14.6.

2 Policy on lifing of aerosystem components

In ascertaining whether or not lifing should be applied to an aerosystem component, the significance of the component must first be determined. The selection processes for significant items, including 43 Structurally Significant Items (SSI) 4,3 can be found in 4Chapter 16.1.1 and JAP(D) 100C-223. A significant item is to be given lifing parameters where it meets the further criteria identified at paragraph 4. Components meeting these criteria are to be allocated a component life, measured in usage. The 4Platform or Commodity Project Team (PT)3 responsible for assessing and promulgating component lives 4is to use3 the criteria and procedures detailed in this chapter.

3 Component failure

3.1 Failure modes

The term ‘failure mode’ refers to the process that leads to the ultimate failure of a component. Typical failure modes include fatigue, overload, ageing (of explosives or textiles), avionic and mechanical wear, cracking, corrosion and general deterioration. A component can suffer from one or more failure modes.

3.2 Critical failure mode

The term ‘critical failure mode’ refers to a failure mode4that causes a failure3likely to result in the loss of the aerosystem concerned, loss of airworthiness or likely to endanger the life of any person concerned with its operation or maintenance.

3.3 Critical components

A significant item that has a critical failure mode is described as a ‘critical component’. The term ‘critical component’ is not applied to components that are duplicated in order to maintain the integrity of the critical function of a system or sub-system.

4 Identification of components to be lifed

The Project Engineer (PE) within 4a PT 3is to determine which failure modes are applicable to each component, consulting with Design Organizations (DOs), Original Equipment Manufacturers (OEMs), equipment 4PTs3 and specialist agencies as necessary. Once identified as a significant item, PEs are to apply lifing to the component when it satisfies both of the following 2 conditions:

1 The component meets one or more of the following criteria:

1.1 Incipient failure, which cannot be detected using condition-monitoring techniques, or the use of such techniques, will impose an unacceptable maintenance penalty.

1.2 It is known or expected that there will be an unacceptable increase in probability of failure after the component has been in service for some time.

2 The component also meets either of the following criteria:

2.1 Failed components significantly affect airworthiness or safety of the aerosystem, or the safety of any person concerned with its operation or maintenance.

2.2 If allowed to fail, components would cause major economic or maintenance penalties.

The lifing of components has severe cost implications both in terms of the scheduled maintenance effort involved and additional provisioning to provide a pool of assets to sustain the repair loop. Therefore, when a decision is made to life a significant item whose failure mode is not critical, the benefits either in terms of increased availability or in through-life support costs must clearly outweigh the other factors involved.

5 Initial assessment of component lives

After identifying components to be lifed,4PTs3 are to assess, for each failure mode that merits allotment of a life, the most cost-effective activity (maintenance, reconditioning or scrapping) that will minimize the occurrence of failures in that mode most effectively. Where a component has more than one failure mode, a different maintenance activity may be required for each mode, giving it a number of lives, eg a bay maintenance life, a recondition life and a scrap life.

5.1 Components justifying fatigue or textile lives

The assessment of components for fatigue or textile failure modes is carried out using data drawn from testing, analysis, calculation, surveillance or experience that determine a failure will occur at a predictable stage within the maximum life envisaged for the system.

5.2 Components subject to deterioration other than fatigue or textile reasons

Components justifying lifing other than for fatigue or textile considerations are dealt with as follows:

1 The 4PT3 PE is to assess in-service component lives by applying the procedures detailed in 4JAP(D) 100C-223.

2 The assessment of lives for new components is based on the design characteristics of the item and knowledge of the failure modes that the life is protecting. This assessment may be provided or based on information from either the DO or other specialist organization, or be based on experience gained using the same or similar components on other platforms.

Where, through lack of necessary data, a PE is unable to allot lives to in-Service components in accordance with 4JAP(D) 100C-223, or to new components in accordance with the DO’s recommendation, the components are to be allotted a provisional 43 life43. The components concerned are then to be subject to a review of lifing measures as described at paragraph 7.1 or, if newly developed, to continued qualification testing. The assessment of provisional lives may affect expenditure on initial spares provisioning and repair facilities. It is therefore essential that any provisional lives allotted are the longest lives that can reasonably be permitted in the circumstances.

5.3 Approval of component maintenance policy

The responsibility for approving the maintenance policy for individual components is vested in the appropriate 4PT3. Due to the cost involved in lifing components, the 4PT3, when deciding the life of a significant item in a failure mode that is not critical, must be confident that the expected improvement in availability or in-Service life support costs will outweigh other considerations.

6 Promulgation of component lives

The 4PT3 is to arrange for the appropriate Schedule Maintenance Agency (SMA) to publish component lives in the Component Life Register (CLR) and Component Replacement List (CRL) of the relevant Topic 5A1 or equivalent publication 4formally agreed by the PE3 and, if appropriate, the Topic 5K, in accordance with the requirements of Chapter 8.1.1. In the case of lifed components with a multi-user application, the equipment 4PT3 is to ensure that relevant platform 4PTs3 are advised of any revised lifing requirements.

6.1 Component life abbreviations

When compiling or amending CRLs and CLRs, the SMA is to use the following abbreviations:

1 Critical Failure Mode – C.

2 Fatigue life – F.

3 Explosive life – E.

4 Textile life – T.

5 Bay maintenance life – BM.

6 Reconditioning life – R.

7 Scrap life – Scrap.

8 Provisional life – P.

9 Shelf Life – SL.

Notes:

1 The annotation for shelf life indicates those components that require periodic maintenance whilst held in storage. The policy for the shelf life and storage of piece-part spares, including elastomerics, is covered in Chapter 5.8 and in JSP 886.

2 4The introduction of the Forward/Depth structure and Integrated Operational Support (IOS) contracts across the MAE has highlighted differences in MoD and Industry terminology to define both “off-aircraft” maintenance and “overhaul”. The respective MoD abbreviations ‘BM’ and “Reconditioning life” may still be used when compiling or amending CRLs and CLRs, but if the particular PT/IOS contract BM and/or Reconditioning life definition requires further clarification it is to be published in the relevant Topic 5A1.3

6.2 Changes to component lives

The promulgation of amendments to published component lives is to be managed in accordance with Chapter 8.2.1 or Chapter 8.2.2. Stns/Ships/Units may be provided with advanced notification of the changes by Routine Technical Instruction (RTI); see Chapter 10.5.3. Advanced notification may allow Stns/Ships/Units to change and/or quarantine components pending the receipt of formal amendment to the Topic 5A1. Advanced notification action is particularly important where component lifing details are contained electronically (LITS, WRAM, etc) and the system affords 4PTs3 the ability to amend details centrally. In the case of lifed components that are the responsibility of an equipment 4PT3, that 4PT3 is to ensure that all relevant platform 4PTs3 are advised of any revised lifing requirements.

6.3 Penalty Factor Numbering (PFN)

Where the same component may be used on different marks or types of aircraft, there may be a requirement to factor the life of the component due to differing operating conditions. Where component lives have a usage factor applied, the Penalty Factor Number (PFN) for each application is to be detailed in the aircraft Topic 5A1 (CRL and/or CLR). Where a 4PT3 considers that an explanation of the management of PFNs is required, it is to be contained in the aircraft Topic 2(N/A/R).

7 Review of lifing measures

Components are assessed during the introduction into service and a life is established. In cases where there is insufficient evidence to determine a lifing policy for a particular component, a provisional life may be promulgated. Components with provisional lives are shown with a suffix (P) in the CRL and may be subject to life sampling procedures. Subsequently, component lives are to be re-assessed as part of an equipment’s schedule review process.

7.1 Review of provisional lives

4PTs3 are to arrange for every component to which a provisional life has been allotted to be subjected to one of the following procedures in order to confirm, extend or remove the provisional life:

1 Continued qualification testing under arrangements made by the 4PT3: normally this is applicable to newly developed components only and is undertaken by the DO or OEM.

2 A life assessment sampling programme conducted in accordance with paragraph 7.2 or other instructions specified by the appropriate PE.

Note:

This paragraph does not apply if it is known that modification action, which will affect the provisional life, is either in progress, or planned, or that the remaining in-Service life of the aerosystem does not justify such action.

The review procedure is to be continued or repeated until either the optimum life is established or it is clear that lifing restrictions can be removed.

When continued qualification testing is undertaken, the PE concerned is to consider the findings and recommendations of the investigating agency and determine what change in the life, if any, should be authorized. If the qualification testing is to be further continued any revised life authorized is still to be a provisional life.

7.2 Procedures for life assessment sampling programmes

7.2.1 4PT3 responsibilities

When a life assessment sampling programme is undertaken, the appropriate4PT3is to:

1 Determine the sampling requirement, taking into account the engineering features and supply status of the component concerned and the total numbers involved; normally a sample batch should consist of at least 6 items.

2 Arrange for publication of the sampling requirement in the Mandatory Fault Reporting Instructions (MFRIs), details of which are at Chapter 7.5.1. If a 4PT3requires notifying that an item is approaching its provisional life, include this in the MFRI.

3 Identify the most appropriate agency to carry out the examination.

4 Authorize a temporary life extension for components still installed in order to avoid further component removals whilst awaiting full reports on the condition of the sample batch. Such a temporary life extension is to be notified by RTI to users; details of the promulgation of changes to component lives are given at paragraph 6. Temporary extensions should normally be long enough to allow all installed components to remain in place until the action required by item 8 below can be completed.

5 Arrange for the rapid assessment and issue of reports, thereby minimizing the requirement for temporary life extensions.

6 Suspend the requirement for further sampling and arrange for MFRIs to be amended accordingly.

7 When a Service unit undertakes component examinations, forward copies of the MOD F761 examination reports to the relevant DO.

8 When sufficient information has been obtained from examination of the sample batch to enable a decision to be made, the4PT3is to take whichever of the following actions is appropriate:

8.1 Allot a new provisional life to the component and issue revised MFRI requirements.

8.2 Allot a non-provisional life to the component. If this life is less than that covered by a temporary extension authorized under the terms of note 4 above, the4PT3PE is also to decide whether any installed components that have exceeded the newly-determined non-provisional life must be replaced immediately.

8.3 Remove life limitations from the component.

9 Irrespective of the procedure adopted for reviewing the provisional life, promulgate any change in component life in accordance with paragraph 6.

7.2.2 Stn/Ship/Unit responsibilities

A Stn/Ship/Unit that removes a component in response to an MFRI life sampling requirement is to:

1 If required, inform the4PT3when a component is approaching its provisional life.

2 Complete an MOD Form 760 in accordance with the requirements of Chapter 7.5.1. The MOD F760 is to be annotated ‘For life sampling examination’.

3 Despatch the component as instructed in the MFRI.

7.3 Review of lives allotted on a non-provisional basis

As part of each maintenance schedule revision, the 4PT3 is to review formally, in accordance with 4JAP(D) 100C-223, all available data pertaining to those component lives that it has authorized on a non-provisional basis. The aim of such reviews is to extend lives to the maximum practicable or, where appropriate, to remove life limitations altogether. If the lives of the components concerned are based on considerations of fatigue, or of ageing of explosives or textiles, 4PTs3 are to conduct their reviews in accordance with any applicable specialist regulations and in consultation with the DO and specialist agencies concerned. On completion of reviews, 4PTs3 are to promulgate any changes in lives in accordance with paragraph 6.

8 Recording of life consumption

A record of life consumed is to be maintained for every lifed component. This record is normally kept within the aircraft MOD Form 700C; however, 4PTs3 may require that some components have their engineering histories recorded on Engineering Record Cards (ERCs). Instructions for the use of ERCs are contained in JAP(D) 100A-02. Alternatively, a record of life consumed may be maintained, if appropriate, wholly by an electronic system and a hard copy of the ERC printed when required.

8.1 Engineering Record Cards (ERC)

On introduction into Service, the 4PT3 is to determine whether a component requires an ERC. The requirement for an ERC is normally determined during the Logistic Support Analysis process. After acceptance into service, the 4PT3 assumes responsibility for managing the ERCs associated with the equipment or assembly. The 4PT3 PE is to:

1 Specify ERC requirements and promulgate them in the relevant section of the Topic 5A1.

2 Ensure that components requiring ERCs have been allocated unique serial numbers.

3 Issue instructions on the disposal of ERCs when aircraft are withdrawn from Service. Because of the possibility of spares recovery programmes, ERCs are normally to be retained until all aircraft of the particular type or types have been withdrawn from Service or the item itself is scrapped.

The SMA is responsible for publishing ERC requirements in the Topic 5A1, including details of the type of ERC to be used for each component.

8.1.1 Mandatory requirement for ERCs

ERCs are to be authorized for equipment in the following categories:

1 An assembly, sub-assembly or component that is allocated a fatigue life.

2 An item whose life is expressed in more than one parameter, eg flying hours, landings and pressurization cycles.

3 An item that requires periodic calibration or proof testing.

4 Aero-engines, modules and accessories.

To provide traceability, supply records for components for which ERCs have been authorized are to be annotated.

8.1.2 Multi-national aircraft components

Components from multi-national aircraft may have differing national requirements for lifing and recording items that are subject to pool repair. Engineering Integrated Logistic Support Managers and 4PT3 PEs of multi-national projects are to make every effort to reach agreement for common documentation. Reference is to be made to JAP(D) 100A-02 when it is proposed to introduce a new multi-national ERC.

8.1.3 Components with fatigue lives aligned to platform/assembly life

Certain dynamic and fixed structural components have fatigue lives that are aligned with the platform/assembly fatigue life and therefore do not require ERCs. However, such components may subsequently be re-lifed due to a change in operational use or design philosophy and it will then become necessary to assess any consumed life. This process is likely to be wasteful if an accurate assessment of consumed life cannot be made. Furthermore, if the assessed life exceeds the imposed life, the component will have to be scrapped. To obviate these problems, 4PTs3 are to consider raising ERCs for specified components that, initially, have ‘unlimited’ lives.

8.1.4 Control of ERCs

ERCs constitute Part D of the aircraft MOD Form 700 and should, where possible, be retained with the MOD Form 700C on the user unit. When a component is removed for maintenance, the ERC is to be completed with details of the removal and the life consumed. The ERC is then to be attached to the MOD F731 and dispatched with the item.

8.1.5 Loss of ERCs

The loss of an ERC is to be reported to an authority level J, who is to quarantine the associated equipment, instigate a full investigation and report his findings to the appropriate 4PT3. If after the investigation the ERC is not found, the appropriate 4PT3 is to authorize the issue of a duplicate ERC (Chapter 7.2.1 paragraph 4.1 refers), or issue disposal instructions as necessary.

8.1.6 Types and relationship of ERCs

ERCs are designed to complement each other when used in connection with major assemblies such as airframes, whilst specific ERCs required to support specific aircraft and associated equipment are listed in the relevant Topic 5A1. The relationship between various ERCs is given below.

8.1.6.1 Airframe

The master ERC for an airframe is the MOD F744 – Airframe Record Card. The associated ERCs are:

1 MOD F745 – Maintenance and Repair Record Card.

2 MOD F746 – Modification Embodiment Record Card.

3 MOD F747 – SI/STI Record Card.

4 MOD F747A series – SI Applications Record.

5 MOD F748 – Miscellaneous Record Card.

6 MOD F751 series – Aircraft Basic Weight and Moment Record Card.

7 MOD F753 – Inspection Test and Modification Certificate.

8.1.6.2 Assembly/ECU

The master ERC for an assembly or ECU is the MOD F749 or MOD F749B series – Assembly Record Card. The associated ERCs are:

1 MOD F753 – Inspection Test and Modification Certificate.

2 MOD F749(ECLS) – Engine Cyclic Life Supplement.

8.1.6.3 Component

An ERC for a component will be selected from one of the following:

1 MOD F735 – Component Log Card (Anglo-French).

2 MOD F735A – Component Record Card.

3 MOD F735B – Engineering Record Card (Tri-National).

A component will also have a MOD F753 – Inspection Test and Modification Certificate.

8.2 Reporting of component change and modification/repair

8.2.1 Component change reporting using Management Information – Engineering Information Services (MI-EIS)

In addition to maintaining records of component lives, Stns/Ships/Units who use MI-EIS for maintenance data recording are to report removals and installations of lifed components, other than those that are solely calendar life expired, on the appropriate form in the MOD Form 707 series. In addition, certain fatigue-lifed assemblies are noted in blocks on the aircraft Flying Log and Fatigue Data Sheet (MOD Form 725); such blocks are to be annotated in accordance with the instructions contained in the relevant MOD Form 799/4F (aircraft type).

8.2.2 Modification/repair of fatigue-lifed components

When a fatigue-lifed component (life in Fatigue Index, Fatigue Hours or Damage Index) has been subject to modification or repair that affects the fatigue life, the fatigue life expired at the time of this action is to be recorded on the ERC. In addition, for aircraft with fatigue analysis carried out by Management Information – Faults and Fatigue (MI F&F), they are to be informed when the modification/repair is carried out. MI F&F will then inform the Stn/Ship/Unit of the latest value of fatigue life consumed on the component. The Stn/Ship/Unit is to enter the details provided on the appropriate ERC.

9 Latitudes to component life

To facilitate maintenance planning and avoid unnecessary restrictions on system availability, some flexibility in the application of authorized lives to individual components is essential. The latitudes permissible for aerosystem components covered by this chapter (see paragraph 1.3) are detailed in paragraphs 9.1, 9.2 and 9.3 below. These latitudes may be limited or prohibited either by the appropriate specialist regulations, by the Front Line Command (FLC) or 4PT3.

9.1 4Project Team (PT) 3responsibilities

9.1.1 Variation and restriction of life anticipation and extension limits

A4PT3 PE may, after considering all the relevant factors, authorize variations in the application of life anticipations and extensions on components, other than those subject to a fatigue life, see paragraph 9.1.2, that are either greater in magnitude or more widely applicable than those detailed in paragraphs 9.2 and 9.3. When circumstances dictate, a PE may also restrict or prohibit the application of extensions. PEs are to publish details of such latitude variations in their Support Policy Statement in the Topic 2(N/A/R) or, where applicable, in the appropriate specialist publication.

9.1.2 Life extension of components subject to fatigue life

4For items subject to a fatigue life, the PE is to determine if it is an SSI or a component, the failure of which would jeopardize the aircraft. In 3such cases any extension to the fatigue life is limited to 1%. Further details on 4SSI and lifed components3 are given in Chapter 416.1.1 and JAP(D) 100C-22.3 An auditable decision process, 4recording advice provided by the DO and,3 risk assessments made, is to support any extension granted under the terms of this paragraph. If, when assessing a fatigue-lifed component for life extension, doubt exists on the status or significance of the component, the PE is to seek guidance from 4Military Aviation Authority Technical Certification Aircraft Structural Integrity (MAA Tech Cert ASI).3

9.2 Anticipation of component lives at Stn/Ship/Unit

An authority level J may authorize the anticipation of any component life expiry. Anticipation of maintenance activities has resource implications; therefore, when anticipating a component life expiry, every effort should be made to ensure that the action does not result in a shortage of components.

9.3 Extension of component lives at Front Line Command (FLC) or Stn/Ship/Unit

9.3.1 Provisional life

The extension of a component subject to a provisional life is prohibited at FLC or Stn/Ship/Unit level.

9.3.2 Fatigue life

The extension of a component fatigue life is prohibited at FLC or Stn/Ship/Unit level.

9.3.3 Explosive life

The extension of an explosive life at FLC or Ship/Station/Unit level is prohibited regardless of whether it applies to either critical or non-critical failure modes; Chapter 14.6 refers.

9.3.4 Textile life

1 The extension of textile scrap lives allotted to safeguard against critical failure modes of components is prohibited at FLC or Ship/Station/Unit.

2 An authority level J may authorize extensions of up to 10% of textile scrap lives allotted to safeguard against non-critical failure modes of components.

9.3.5 Bay maintenance life

An authority level J may authorize extensions to bay maintenance lives as follows:

1 Up to 10% on components with lives allotted to safeguard against critical failure modes.

2 Up to 25% on components with lives allotted to safeguard against non-critical failure modes.

9.3.6 Reconditioning life

An authority level J may authorize extensions of up to 10% on reconditioning lives allotted to safeguard against either critical or non-critical failure modes.

9.3.7 Scrap life

When the extension of a scrap life is being contemplated, the reason for the lifing must be fully understood. The scrap life may have been applied for fatigue reasons and not for economic or reliability concerns: therefore, an authority level J may:

1 Not authorize the extension of scrap lives allotted to safeguard against critical failure modes of components.

2 Extend components by up to 10% except where extensions would cause fatigue 43lives, allotted to safeguard against non-critical failure modes, to be exceeded.

4Notes3:

1 Before extending a component life, a check is to be made as to whether that component contains an explosive sub-component. If it does, the extension granted is not to compromise the life of the explosive component; see Chapter 14.6.

2 4If a component, which is extended to align with an aircraft/equipment extension, is subsequently removed from the aircraft/equipment the extension is invalidated.3

10 Unlifed components liable to fatigue damage

Some components that have a critical function and are susceptible to fatigue damage, and which may or may not have been separately provisioned, are not normally lifed because:

1 Their fatigue lives equal or exceed those of their parent assemblies, and

2 They are not expected, in the course of normal maintenance, to be transferred between parent assemblies, eg between airframes.

If, exceptionally, such a component is transferred from its original parent assembly to another, there is an obvious risk that the fatigue life of the component may be exceeded. To safeguard against this eventuality, 4PT 3PEs are to identify such components and arrange for them to be listed in the preliminary pages of the Topic 5A1 under the heading ‘Log Card Required on Transfer Between Parent Assemblies’. Where such components need to be transferred from aircraft that are being, or have been, withdrawn from Service, PEs are to ensure that fatigue records for the donor aircraft are retained for as long as such components may be required.

Should one of the listed components, or one which the responsible engineering officer of the Stn/Ship/Unit considers should have been so listed, be transferred between parent assemblies, the responsible engineer concerned is to:

3 Open an ERC for the component and, pending action by the appropriate 4PT3 PE, assign to the component a fatigue life equal to that of the parent assembly.

4 Determine and enter on the ERC the fatigue life consumed by the component at the time of transfer, together with the aircraft tail number or other identification of the donor assembly and, where possible, the date the component was fitted. In the absence of any other information, the component life consumed is to be assumed to be that of the donor assembly and the ERC is to be annotated ‘estimate’.

5 Report details of the transfer to the 4PT.3

The 4PT3 is to consider, assess and, where appropriate, promulgate a life for the component. Any component life so promulgated is to be annotated ‘Log card required on transfer between parent assemblies’. 4A PT3 PE who decides not to promulgate a life is to provide the Stn/Ship/Unit reporting the transfer with instructions on the lifing or other action to be taken.

11 References

This chapter refers to the following publications:

1 4JAP (D) 100C-22 – Guide to Developing and Sustaining Preventive Maintenance Programmes.3

2 AP 100E-01B – Handbook of Removal Criteria for Aero engines, Accessories and Ancillaries.

3 JSP 886 – The Defence Logistics Support Chain Manual

4 JAP(D) 100A-02 – Military Aviation Engineering Documentation Procedures.

5 Topic 2(N/A/R) – General Orders, Special Instructions and Modifications.

6 Topic 5A1 – Master Maintenance Schedule.

7 Topic 5K – Schedule of Component Lives (RN only).