AD/B727/109 Amdt 1 - Fuselage - Aft Lower Lobe Frame (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Boeing 727 Series Aeroplanes

AD/B727/109 Amdt 1

Applicability: All Models.

Fuselage - Aft Lower Lobe Frame 1/93

Requirement: 1. Visually inspect aircraft for cracks in accordance with Boeing S.B. 727-53-AO195, Revision 1, dated 19 September 1991.

2. Incorporate the preventative modification specified in Boeing S.B. 727-53-AO195, Revision 1, Accomplishment Instructions, Part II.

Modified areas are exempt from the inspections of 1. above.

Note: FAA AD 90-06-16, Amendment 39-6545 refers.

Compliance: 1. (a) If previously inspected in accordance with the original issue of this AD - at intervals not to exceed 4000 flight cycles; otherwise,

1. (b) Prior to exceeding 28000 flight cycles, or before 10 June 1993, whichever is the later, and thereafter at intervals not to exceed 4000 flight cycles.

2. Prior to exceeding 47500 flight cycles, or prior to 9 March 1994, whichever is the later.

Background: There have been reports of cracks in aft lower lobe frames in a number of aircraft which had accumulated between 41500 and 59600 flight hours, and between 29800 and 51600 flight cycles. Cracking is attributed to fatigue, and if not repaired could result in cracks in the skin, hence pressurization loss. Severed frames could result in rapid crack growth and subsequent rapid decompression.

Since the original issue of this AD, further reports of cracking in low time aircraft have necessitated a reduction in the inspection threshold. The FAA has determined that an adequate level of safety cannot be maintained by means of inspection alone, and that the preventative modification should be mandatory. A terminating modification is now also available for stringers S-28 left and right. These changes are reflected in Amendment 1 of this AD.