AD/A330/76 Amdt 1 Electrical Power/APU Generator Inspection (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/A330/76 and issues the following 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 Amdt 1 Electrical Power/APU Generator Inspection 10/2007 TX

Applicability:

Airbus A330 all certified models.

Requirement:

Action in accordance with EASA AD 2007-0188R1 dated 24 July 2007.

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

Compliance:

As specified in the requirement document.

This Amendment becomes effective on 26 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 CASA AD/A330/73 Amendment 1.

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

The current amendment mirrors the requirements and compliance schedules of EASA  AD 2007-0188 Revision 1.

The original issue of this AD became effective on 16 July 2007.

David Punshon
Delegate of the Civil Aviation Safety Authority

25 July 2007