AD/B747/354 Crown Crease Beam (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/B747/354 Crown Crease Beam 3/2007

Applicability:	Model 747-100B SUD, -200B, -300, -400, -400D, and 747SP series aircraft; as identified in Boeing Alert Service Bulletin 747-53A2591 original issue, or later FAA approved revision.
Requirement:	Action in accordance with the technical requirements of FAA AD 2007-01-09 Amdt 39-14881.
Compliance:	As specified in the Requirement document, with a revised effective date of 15 March 2007.
This Airworthiness Directive becomes effective on 15 March 2007.
Background:	The FAA received a report of cracking of the crown crease beam on two Model 747 aircraft.  Such cracking, unless detected and corrected, could expand and result in depressurisation and inability of the airframe structure to sustain flight loads.

David Villiers
Delegate of the Civil Aviation Safety Authority

1 February 2007