AD/B747/393 Section 41 Upper Deck Floor Beam Upper Chords (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.

Boeing 747 Series Aeroplanes

AD/B747/393 Section 41 Upper Deck
Floor Beam Upper Chords 7/2009

Applicability:	Model 747-400 and -400D series aircraft, as identified in Boeing Alert Service Bulletin 747-53A2688, dated 21 August 2008, or later FAA approved revision.
Action in accordance with the technical requirements of FAA AD 2009-10-06 Amdt 39-15901.
Compliance:	As specified in the Requirement document, with a revised effective date of 2 July 2009.
This Airworthiness Directive becomes effective on 2 July 2009.
Background:	The FAA received reports of cracks that were detected in the Section 41 upper deck floor beam upper chords.  Such cracking, unless detected and corrected, could result in severing of the floor beams with consequent rapid decompression or reduced controllability of the aircraft.

David Villiers
Delegate of the Civil Aviation Safety Authority

22 May 2009