AD/B747/224 Amdt 1 - Upper Deck Floor Beams (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/B747/224 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/B747/224 Amdt 1 Upper Deck Floor Beams 6/2005

Applicability: Model 747-100, -100B, -100B SUD, -200B, and -300 series aircraft; and Model 747SR and 747SP aircraft; as listed in Boeing Alert Service Bulletin 747-53A2431 Revision 2, dated 13 June 2002. Requirement: Inspect in accordance with the technical requirements of FAA AD 2005-06-11 Amdt 39-14019. Compliance: As specified in the Requirement document, with a revised effective date of 9 June 2005. This Amendment becomes effective on 9 June 2005. Background: The FAA received a report from the manufacturer that, during a fatigue test, the upper chord and web of the upper deck floor beams located at body stations 340 and 360 were found severed at approximately 34,000 flight cycles. Another report by an operator indicated that a severed upper chord and web were found in the upper deck floor beam at body station 38 at approximately 33,000 total flight cycles.

Amendment 1 is issued in response to a new FAA AD, which lowers the threshold for the existing inspections and requires new repetitive inspections of previously repaired areas, and repair if necessary. This new FAA AD was prompted by the results of an additional detailed analysis that indicate fatigue cracks can initiate sooner than has previously been observed.