Ad/A320/178 Amdt 1 - Trimmable Horizontal Stabilizer Actuator (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/A320/178 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 A319, A320 and A321 Series Aeroplanes

AD/A320/178 Amdt 1 Trimmable Horizontal Stabilizer Actuator 10/2006

Applicability:

AIRBUS A318, A319, A320 and A321 aircraft.

Requirement:

1.    Do a check of the clearance between secondary nut trunnion and junction plates at the lower Trimmable Horizontal Stabilizer Actuator (THSA) attachment, and if necessary correct any defects found in accordance with the instructions detailed in AIRBUS Service Bulletin (SB) A320-27-1164 Revision 4 or later DGAC approved revisions.

2.    Repeat the inspections as detailed in Requirement 1 of this Directive.

3.    Inspect the upper THSA attachment and, if necessary, correct any defects found in accordance with the instructions detailed in SB A320-27-1164 Revision 4 or later DGAC approved revision.

4.    Repeat the inspections as defined in requirement 3 of this AD.

5.    Report the findings of the inspections to AIRBUS through page 2 of appendix 01 of SB A320-27-1164 Revision 4 “inspection reporting sheet”.  Nil findings do not need reporting.

Note:  EASA AD 2006-0223 dated 21 July 2006 refers. This AD supersedes DGAC AD 2006-051.

Compliance:

1.    Unless already accomplished, within 20 months since first flight or within 600 flight hours from 7 July 2005 (the effective date of the original issue of this AD), whichever occurs later.

Aircraft that have been inspected in accordance with SB A320-27-1164 Revision 2 or 3 are compliant with this requirement.

2.    At intervals not exceeding 20 months.

3.    Within 10 months since first flight following introduction of the aeroplane into service; Or

Within 10 months from last inspection of the upper THSA attachment as per SB A320-27-1164 Revision 2 or 3; Or

Within 100 days from the effective date of this AD, whichever occurs later.

Do not exceed 20 months from last inspection of the upper THSA attachment as per SB A320-27-1164 Revision 2 or 3.

4.    At intervals not exceeding 10 months.

5.    Upon completion of the inspections.

This Amendment becomes effective on 28 September 2006.

Background:

The THSA has been tested on rig in order to check its behaviour in case of primary load path failure.  In that configuration, the loads are transferred to the secondary nut, which should jam, preventing any THS motion.

Tests have shown that the secondary nut did not jam as expected, preventing the detection of the primary load path failure.

Since the issue of the original version of this AD, further tests have been performed on the secondary load path which highlighted the need to reduce the interval for the THSA upper attachment inspection to 10 months.

The original issue of this AD became effective on 7 July 2005.

James Coyne
Delegate of the Civil Aviation Safety Authority

14 August 2006