AD/B747/377 Fuselage Exterior Skin at Station 488 (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/B747/377 Fuselage Exterior Skin at Station 488 7/2008

Applicability:	Model 747-200F, -300, -400, and -400D series aircraft; as identified in Boeing Service Bulletin 747-53A2685 Revision 1, or later FAA approved revision.
Requirement:	Action in accordance with the technical requirements of FAA AD 2008-09-20 Amdt 39-15501.
Compliance:	As specified in the Requirement document, with a revised effective date of 3 July 2008.
This Airworthiness Directive becomes effective on 3 July 2008.
Background:	The FAA received reports of missing fasteners from the shear clip of the sub frame to auxiliary sill joint and cracking of the adjacent exterior skin and internal doubler.  Missing fasteners could result in cracks in the adjacent exterior skin and internal doubler, which can propagate and result in loss of structural integrity and sudden in-flight decompression of the aircraft.

David Villiers
Delegate of the Civil Aviation Safety Authority

16 May 2008