Ageing Aircraft Industry perspective - egnos-africa.com SIASA... · Airbus design office and...

SIASA project

This project is funded by the European Union and implemented by EASA.

TE.GEN.00409-001

Ageing Aircraft Industry perspective

Graeme Riddick Airworthiness Engineer (Structure and Systems installation) Technology Evolution – Impact on Airworthiness 23-24 September 2014, Windhoek, Namibia

23-24 September 2014 Technology Evolution - Impact on Airworthiness, Windhoek, Namibia 2

Ageing aircraft - Agenda

Airbus certification & ageing aircraft

Corrosion

Widespread Fatigue Damage


Ageing aircraft - Certification


Ageing aircraft safety rules

Fatigue critical structure

Maintenance

Corrosion


Ageing aircraft safety rules

Regulatory context

History Mentioned by EASA

Airbus design office and certification teams working to respect delivery schedule

Working with EASA but also other authorities

AMC 20-20 Continuing Structural Integrity Programme

Maintenance Requirements for operators

In all cases Airbus ultimately supports all operators to comply with improved Ageing Aircraft Safety Rules.


AASR - Principles

Past

Review all modifications

Evaluate repairs

Future

Update ICA

All future modifications to include DTE


Approved Airbus Manuals

In the Airbus context what are “ICA” ?

AMM – Aircraft Maintenance Manual Contains General and Detailed inspection instructions

Requires inspection for corrosion damage

SRM – Structure Repair Manual Covers damage classification and repair

Corrosion prevention

ALS – Airworthiness Limitations Section Part 1 – Safe Life Items

Part 2 – Damage Tolerant Items

MRBR – Maintenance Review Board Report

NTM – Non-destructive Testing Manual


AMC 20-20

Identification of Fatigue Critical Structure “is structure that is susceptible to fatigue cracking that could lead to a catastrophic failure of an aircraft “

Repair Evaluation Guidelines “provide a process to establish damage-tolerance inspections for repairs that affect Fatigue Critical Structure “

Damage Tolerance Evaluation “a process that leads to a determination of maintenance actions necessary to detect or preclude fatigue cracking that could contribute to a catastrophic failure”


Defining the FCBS

Fatigue Critical Baseline Structures criteria: Metallic PSE

Structures whose failure or detachment could compromise continued safe flight and landing by an adverse effect on a PSE.

(as defined in §25.571)

Fatigue critical structure

The approved list was communicated to operators via the SRM (e.g. A320 SRM 51-11-12)


Fatigue Critical Baseline Structure (FCBS)


Complete structure

Primary structure Secondary structure

PSE

Metallic PSE •Secondary structure

part of FCBS

FCBS

• Composite PSE •Detail Design Points

Damage Tolerance Evaluation

For existing repairs

SRM updated where necessary to include

Repair Category

Inspection details where relevant

Repair Evaluation Guidelines to help operators evaluate existing repairs through one-time repair survey.

REG is added to the list of ICAs


Damage Tolerance Evaluation

For repairs via SBs and ADs

Review of all published SBs and ADs

For future repairs

Repair approval process that takes into account DT aspects when necessary

For modifications to FCS or creating new FCS

Same process


Support from the EASA

EASA has supported Airbus by reviewing the FCS lists and REG and recommending approval.

The SRM and all repair data is approved by Airbus under their EASA Part 21 Approval

All DTI for modifications/alterations are approved by EASA using the existing processes for modification approval


For operators and authorities

What operators must do:

Use REG for one-time repair survey

Systematic DTE for repairs/modifications/alterations performed to FCS

For authorities

Take AASR into account

All the work has been done – but it relies on your feedback and monitoring





Corrosion


Corrosion

Airbus design aimed at preventing corrosion

Corrosion is addressed in all maintenance documents

Covered by MRB tasks

Airbus ICA include a systematic approach to corrosion identification





Corrosion


Wide Spread Fatigue Agreement

Airbus and Authorities agree that

•Without intervention, MSD/MED is inevitable

• Inspection (Safety by Inspection) should not be relied on to prevent an occurrence of WFD

•Structural replacement/modification (Safety by Replacement) should be the primary line of defense against WFD - any inspections, if practical, are supplementary


Question

How long can an aircraft be safely operated ?

An airplane can be operated safely forever if the proper maintenance is performed


What is proper maintenance?

Changes & increases with time in service

Always based on a finite amount of knowledge

Analyses performed

Fatigue tests completed

Service experience (positive & negative)

Teardown inspections of high time airplanes

Proper maintenance for an airplane usually consists of maintenance actions that are developed proactively and reactively


Limit of validity

The LOV is how far out we can validate what the proper maintenance needs to be performed in order to prevent WFD.

Airbus approach to LOV:

Identify airplane configuration

Identify “candidate LOV”

Identify structure susceptible to WFD

Perform WFD evaluations

Propose LOV


Identifying WFD-susceptible structure

Subset of fatigue critical structure that has:

Similar details in the same element working at the same stress level

Similar adjacent elements working at the same stress level



Using advisory material



Airbus engineering analysis


•Frame foot fitting

•Frame segment

•Crack location

WFD Evaluations


WFD Evaluations

In-Service Experience

Positive findings from destructive inspection

Negative findings with large number of hours and cycles

Typically used for mature fleet (e.g. A300).

Important to report findings through the right channels to ensure that findings are taken into account by Airbus Engineering

Laboratory Testing

Must use fatigue testing (existing and new airplanes) Coupons, Components, Full-scale articles

With and without teardown inspections


A300 Approach


A300 Aircraft LOV Objective

(60 000FC)

WFD Evaluation

MSB ISB ALS Grace Period

Binding Schedule

Binding schedule

If the LOV depends on maintenance actions?

what happens?

• If service information for these maintenance

actions has not been issued, Airbus must submit a

list of those actions and a binding schedule for

development of these actions

Schedule:

• Mods available in a reasonable time frame before the need to apply it (design, plan, plan order kit, AD process)


Question

How long can an aircraft be safely operated ?

An airplane can be operated safely until LOV if the proper maintenance is performed


Conclusion

Ageing aircraft safety

Covered by aircraft certification

Requires proper maintenance

Requires feedback from operators and local authorities

Airbus

Has shown compliance to ageing aircraft safety requirements

Provides necessary document to operators to comply with maintenance requirements

Local authorities

Consider EASA requirements on ageing aircraft


SIASA project

This project is funded by the European Union and implemented by EASA.

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Ageing Aircraft Industry perspective - egnos-africa.com SIASA... · Airbus design office and...

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