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Project MS 10/28 - Provide Industry with a DP that describes how the FAA have set regulatory requirements aimed to reduce the risk of catastrophic failure of transport category aircraft

Topic code: 
Maintenance/Maintenance personnel
Project status: 
Closed

History

This project is now closed.

15 Dec 2011

Provide Industry with a DP that describes how the FAA have set regulatory requirements aimed to reduce the risk of catastrophic failure of transport category aircraft

This project is now closed.

Refer to the project closure notes for further information.

26 Jul 2011

DP 1008CS - Continued Airworthiness and Safety Improvements for Transport Category Aircraft

DP 1008CS has been published. Your comments are requested by 21 October 2011.

23 Dec 2010

Provide Industry with a DP that describes how the FAA have set regulatory requirements aimed to reduce the risk of catastrophic failure of transport category aircraft

Project approved.

Closure notes

Project closed 15 December 2011.

Following the closure of the DP consultation period, CASA will consider responses to the DP and relevant EASA Notices of Proposed Amendments (NPA) on the topics covered by the DP. Any Australian rule making activity generated as a result of the DP and subsequent FAA/EASA rules will be announced as a future and separate project

Issue

Documentation provided by the FAA explains that fuel tank explosions have been a constant threat with serious aviation safety implications for many years. Since 1960, some 17 aeroplanes have been destroyed as the result of a fuel tank explosion and four fatal aeroplane accidents have been caused by fuel tank explosions since 1989. Safety concerns about wiring systems in aeroplanes were brought to the forefront of public and governmental attention by a 1996 accident over the Atlantic Ocean near East Moriches, New York, involving a 747-131 aeroplane, operated as TWA Flight 800. The probable cause of the TWA Flight 800 accident, in which the aeroplane broke up in flight, was an explosion of the centre wing fuel tank, resulting from ignition of the flammable fuel and air mixture in the tank. The most likely source of ignition energy for the explosion was a wiring failure in the fuel quantity indication system outside the centre wing tank.

In response to the fuel tank explosions and the potential for aged wiring systems to cause the ignition of explosions, FAR now have requirements to deal with both matters. In relation to aged wiring, the requirements organise and clarify design requirements and add new certification rules for wiring. Holders of Type Certificates (TC) for certain Transport Category aeroplanes are required to make changes to existing wiring Instructions for Continued Airworthiness (ICA) for incorporation into the aircraft maintenance program.

The flow on effect of those changes is that registered operators are also required to incorporate ICA for fuel tank systems into their maintenance/inspection programs.

In relation to fuel tank flammability, the requirements establish performance-based requirements that set acceptable levels of flammability exposure in tanks most prone to explosion or alternatively require the installation of an ignition mitigation means (IMM) in an affected fuel tank.

As well as addressing fuel explosion concerns the FAA have developed regulations to deal with fatigue cracking. Structural fatigue cracking of aging aeroplanes has been a major aviation safety concern for many years. If not detected and repaired, fatigue cracking can eventually lead to catastrophic structural failure and loss of the aeroplane. Damage tolerance inspections (DTI) are one way to preclude catastrophic failure resulting from fatigue cracking; but these inspections need to take into account any adverse effects that repairs and alterations may have on fatigue life, or on the capacity to carry out inspections on fatigue critical structures. Currently there is no Australian requirement for repair and alteration designers to provide DT data to accompany the design or alteration.

In light of that the FAR now contains requirements for the holders of design approvals, to make available to operator?s, DT data for repairs and alterations to fatigue critical aeroplane structures.

Project Objective

The objective of the project is to develop a discussion paper that presents information for public and industry consideration. This activity would be carried out in conjunction with CASA evaluation of the issue and response to the equivalent EASA (Notices of Proposed Amendments (NPA) and consultation consideration of these same matters.

Project Status

This project was approved by Peter Boyd, EM Standards Development and Future Technology Division on 22 December 2010.

Project management

Project Leader: Mark Bathie

Project Stakeholder: Peter Boyd, EM Standards Development and Future Technology Division

Standards Officer: Mike Broom

Project Priority

Low