AD/B747/294 Amdt 1 Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure (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/B747/294 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/B747/294 Amdt 1 Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure 7/2006

Applicability:

All Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D,
-400F, 747SR, and 747SP series aircraft.

Requirement:

Action in accordance with the technical requirements of FAA AD 2006-10-16 Amdt 39-14600.

Note:  Boeing Alert Service Bulletins 747-55A2050 and 747-55A2050 Revision 1, or later FAA approved revision, refer.

Compliance:

As specified in the Requirement document, with a revised effective date of
6 July 2006.

This Amendment becomes effective on 6 July 2006.

Background:

The FAA received numerous reports of cracking from two operators of six Model 747 series aircraft.  Of the 22 reports of cracking received, 20 of the reports were in an area not covered by the Zone A inspections required by FAA AD 2002-06-02 (AD/B747/271).  The original issue of this Directive required certain inspections to detect such cracking, which undetected, could lead to reduced structural capability of the outboard and centre sections of the horizontal stabiliser, and result in loss of controllability of the aircraft.

Amendment 1 is issued in response to a new FAA AD, which was prompted by reports of cracking in the outboard and centre section of the aft upper skin of the horizontal stabiliser, the rear spar chord, rear spar web, terminal fittings, and splice plates; and a report of fractured and cracked steel fasteners.  This Directive adds, for certain aircraft, repetitive inspections for cracking of the outboard and centre sections of the horizontal stabiliser, and repair if necessary, and for certain other aircraft adds a detailed inspection to determine the type of fasteners; and additionally, revises the compliance times for certain inspections and adds alternative inspections for cracking of the upper skin of the centre section and rear spar upper chord.  This Directive incorporates the requirements of AD/B747/271 (AD 2002-06-02).

David Villiers
Delegate of the Civil Aviation Safety Authority

25 May 2006