AD/B747/168 Amdt 3 - Engine Pylon Aft Torque Bulkhead (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/B747/168 Amdt 2 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.

Boeing 747 Series Aeroplanes AD/B747/168 Amdt 3 Engine Pylon Aft Torque Bulkhead 8/2009

Applicability: Model 747 series aircraft, as listed in Groups 1, 2, and 5 of Boeing Alert Service Bulletin (ASB) 747-54A2184, Revision 1, dated 6 May 1999. Requirement: Action in accordance with the technical requirements of FAA AD 2000-12-16 Amdt 39-11794. Compliance: As specified in the Requirement document with a revised effective date of 7 September 2000.

The compliance remains unchanged by issue of the Directive. This Amendment becomes effective on 30 July 2009. Background: The FAA received two reports of cracking of the aft torque bulkhead at the number 1 and number 2 engine pylons. This cracking occurred on a Boeing model 747-200F series aircraft powered by Rolls Royce model RB211 series engines. Cracking of the aft torque bulkhead at the engine pylons, if not detected and corrected in a timely manner, could result in failure of a pylon and consequent separation of the engine from the wing.