AD/A320/226 Trimmable Horizontal Stabilizer Actuator (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 A319, A320 and A321 Series Aeroplanes
| AD/A320/226 | Trimmable Horizontal Stabilizer Actuator | 11/2008 |
Applicability: | AIRBUS A318-111, A318-112, A318-121, A318-122, A319-111, A319-112, |
Requirement: | 1. Perform a check of the clearance between the secondary nut trunnions and the junction plates at the lower THSA attachment, visually inspect the lower attachment for correct installation of attachment parts, and carry out the applicable corrective actions, in accordance with AIRBUS Service Bulletin (SB) A320-27-1164 Revision 6 dated 1 April 2008. 2. Inspect the upper THSA attachment for correct installation, cracks, damage and metallic particles, and carry out the applicable corrective actions in accordance with AIRBUS SB A320-27-1164 Revision 6. 3. Report to AIRBUS, using the Appendix 01 “inspection reporting sheet” of SB A320-27-1164 Revision 6 when any findings have been made. The use of later approved revisions of AIRBUS SB A320-27-1164 is acceptable for compliance with the requirements of this AD. Note: EASA AD 2008-0150 dated 5 August 2008 refers. |
Compliance: | For Requirement 1 - Within 20 months since first flight of the aircraft or within 20 months since the last inspection in accordance with AIRBUS SB A320-27-1164 Revision 2, 3, 4 or 5, whichever occurs later after the effective date of this AD. Thereafter repeat the inspection at intervals not exceeding 20 months. For Requirement 2 - Within 10 months since first flight of the aircraft or within 10 months since the last inspection in accordance with AIRBUS SB 27-1164 Revision 2, 3, 4 or 5, whichever occurs later, after the effective date of this AD. Thereafter repeat the inspection at intervals not exceeding 10 months. For Requirement 3 - Within 30 days after each check/inspection as required by this AD. |
| This Airworthiness Directive becomes effective on 23 October 2008. | |
Background: | The Trimmable Horizontal Stabilizer Actuator (THSA) of the A320 Family aircraft 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. In order to verify the integrity of the THSA primary load path, AD/A320/178 required two repetitive inspections to obtain confirmation that the secondary load path is not loaded. While performing these repetitive inspections, several occurrences of an incorrect installation of the THSA have been found. This condition, if not corrected, could lead to a degradation of the integrity of the THSA primary load path and to secondary load path partial or full engagement. To address these findings, AD/A320/207 required a one-time detailed visual inspection of specific parts of the THSA attachments. This AD retains the requirements of AD/A320/178 Amendment 1 and AD/A320/207, which are superseded, and in addition requires repetitive detailed visual inspections of specific parts of the THSA attachments. |
James Coyne
Delegate of the Civil Aviation Safety Authority
26 August 2008
0
0
0