AD/A330/76 Electrical Power/APU Generator Inspection (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Airbus Industrie A330 Series Aeroplanes

AD/A330/76 Electrical Power/APU Generator Inspection 9/2007 DM

Applicability:

Airbus A330 all certified models, all serial numbers.

Requirement:

Action in accordance with EASA AD 2007-0188-E.

Note:  Airbus All Operator Telex (AOT) A330-24A3044 original issue or later EASA approved revisions refer.

Compliance:

As specified in the requirement document.

This Airworthiness Directive becomes effective on 16 July 2007.

Background:

Two A330 operators have reported uncontained APU generator failures on ground.

Preliminary investigations confirmed an uncontained APU Generator failure with subsequent aircraft structural damages to the APU compartment and, in one case, to the stabiliser compartment.

Further investigations are ongoing to determine the root causes.  It has been evident that for both events, this unknown root cause initiates a collapse of the Drive End Bearing (DEB) leading to an uncontained failure.  Evidence shows also that the DEB failures were not instantaneous, and therefore, the detection of small debris could indicate early stage DEB failure.

A one-time inspection for detection of large-scale debris in the Generator Scavenge inlet screen (last chance filter) of the APU allowing to identify APU Generator in a state close to failure has been rendered mandatory by Airworthiness Directive (AD) 2007-0080R1.

The aim of this Emergency AD (EAD) is to mandate a repetitive inspection of the APU generator Scavenge filter element and filter housing and APU Generator Dain plug for signs of small debris coming from the APU Generator and therefore to detect an APU Generator failure in an early stage.

The EAD was originally published as PAD 07-119, which is now cancelled and replaced by this Emergency AD.

David Punshon
Delegate of the Civil Aviation Safety Authority

13 July 2007