AD/ATR 42/20 Main Landing Gear Side Brace Assembly (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.

Avions de Transport Regional ATR 42 Series Aeroplanes

AD/ATR 42/20 Main Landing Gear - Side Brace Assembly 12/2007 DM

Applicability:

ATR 42-200, 42-300 and 42-320, all serial numbers, unless MLG side brace assemblies P/N D22710000 with suffix “-9” are installed on both sides, as specified in ATR Service Bulletin (SB) ATR 42-32-0092 (ATR modification No. 8463).

Requirement:

Carry out inspections and actions as required by EASA AD 2007-0263, dated
3 October 2007.

Note:  The referenced EASA AD 2007-0263 supersedes EASA AD 2007-0112, issued 27 April 2007.

Compliance:

As per requirement document (EASA AD 2007-0263), with a revised effective date of 25 October 2007.

This Airworthiness Directive becomes effective on 25 October 2007.

Background:

An ATR 42-300 experienced a collapse of the Right (Starboard) Main Landing Gear when taxiing.  The cause of the failure was subsequently found to be a crack in the side brace assembly originating from a corrosion pit in a very highly stressed area of the upper arm.  The dimensions of the corrosion pit were lower than the minimum defect size that can be detected during overhaul inspections.

This AD is issued to require re-inspection of MLG side brace assemblies previously inspected in accordance with Rev 1 of Messier Dowty SB 631-32-191 and reduces the inspection interval initially proposed in EASA AD 2007-0112 in order to maintain the same level of confidence.

David Villiers
Delegate of the Civil Aviation Safety Authority

5 October 2007