AD/A330/93 Spoiler Servo Maintenance Cover (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/A330/93 Spoiler Servo Maintenance Cover 12/2008

Applicability:

AIRBUS A330 aircraft, models -301, -302, -303, -321, -322, -323, -341, -342 and
-343, all serial numbers up to and including MSN 588 except those on which AIRBUS Service Bulletin (SB) A330-27-3110 has been embodied in service.

Requirement:

Carry out the actions detailed in paragraphs A, B and C of EASA AD 2008-0160.

Compliance:

In accordance with the compliance times detailed in EASA AD.  For the purposes of this AD the effective date shall be read as 20 November 2008.

This Airworthiness Directive becomes effective on 20 November 2008.

Background:

One Long Range operator experienced a failure of one spoiler servo-control, associated with surface deflection in flight and hydraulic leak.  On ground, this servo-control Part Number (P/N) MZ4306000-02X was found with the maintenance cover broken.  Investigations showed that the rupture of the maintenance cover was due to pressure pulse fatigue.

The maintenance cover allows switching the servo-control from “Operational” to “Maintenance” modes.  The same cover is installed on all standard MZ spoiler servo-controls except on P/N MZ4339390-12 and MZ4306000-12, which have a reinforced maintenance cover.  The rupture of the maintenance cover in flight may result in the deflection of the associated spoiler surface up to the null-hinge position (loss of the hydraulic locking).  It may also result in the loss of the associated hydraulic system (external leakage).  In the worst case, the three hydraulic systems may be affected, which constitutes an unsafe condition.

For the reasons described above, this AD requires the identification and the modification of all standard MZ spoiler servo-controls with initial maintenance cover (P/N MZ4339390-01X, -02X, -10X for position 1 and P/N MZ4306000-01X, -02X,
-10X for positions 2 to 6) into standard MZ servo-controls with reinforced maintenance cover (P/N MZ4339390-12 for position 1 and P/N MZ4306000-12 for positions 2 to 6).

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

3 October 2008