AD/SF340/99 MLG Shock Strut and Axle Adaptors (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.

SAAB SF340 Series Aeroplanes

AD/SF340/99 MLG Shock Strut and Axle Adaptors 11/2006

Applicability:

Model SF340A aircraft, serial numbers SF340A-004 through -159, unless equipped with main landing gear (MLG) shock struts modified in accordance with APPH Ltd. Service Bulletin (SB) AIR83022-32-32 or SB AIR83064-32-12.

Model 340B aircraft, serial numbers 340B-160 through -459, unless equipped with MLG shock struts modified in accordance with APPH Ltd. SB AIR83064-32-12.

Requirement:

1.    Inspect the MLG in accordance with SAAB SB 340-32-133 original issue, or at latest EASA approved revision.

2.    Inspect and modify the MLG shock strut and axle adaptors in accordance with Attachment 1 to SAAB SB 340-32-133 original issue, or at latest EASA approved revision, (APPH Ltd. SB AIR83022-32-32) or Attachment 2 (APPH Ltd. SB AIR83604-32-12).

Note:  EASA AD 2006-0263 refers.

Compliance:

1.    Within 8,000 flight cycles since the last MLG overhaul, or within 1,500 flight cycles or 6 months after 26 October 2006, whichever occurs later.  Inspect thereafter at intervals not to exceed 2,000 flight cycles, until Requirement 2 is accomplished.

2.    At the next MLG overhaul after 26 October 2006.

This Airworthiness Directive becomes effective on 26 October 2006.

Background:

A crack was detected in an MLG axle adaptor during fatigue testing.  Investigation revealed the internal edges of the dowel holes did not have the correct radius, and the crack had propagated from the edge of one of the dowel holes.  Failure of the axle adaptor could lead to wheel separation and total loss of brake capability.

David Villiers
Delegate of the Civil Aviation Safety Authority

14 September 2006