COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 737 Series Aeroplanes
AD/B737/129 Aft Pressure Bulkhead Web 6/99
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Applicability: All Model 737-100, -200, -200C, -300, -400, and -500 series aircraft.
Requirement: Conduct initial and repetitive inspections in accordance with the technical requirements of FAA AD 99-08-23 Amdt 39-11132.
Note: Boeing 737 Non Destructive Test Manual D6-37239, Part 6, Section 53-10-54, dated December 5, 1998 refers.
Compliance: For aircraft that have accumulated 40,000 or more total flight cycles:
Inspect within 375 flight cycles or 60 days after 10 May 1999, whichever occurs later.
For aircraft that have accumulated 25,000 or more total flight cycles and fewer than 40,000 total flight cycles:
Inspect within 750 flight cycles or 90 days after 10 May 1999, whichever occurs later.
For aircraft that have accumulated fewer than 25,000 flight cycles: Inspect prior to the accumulation of 25,750 total flight cycles.
Within 1,200 flight cycles after performing the initial inspection requirement of this Directive, and thereafter at intervals not to exceed 1,200 flight cycles:
Perform either the low frequency eddy current inspection or detailed visual inspection specified in the Requirement document of this Directive.
This Airworthiness Directive becomes effective on 5 May 1999.
Background: The FAA received reports of fatigue cracking found on Boeing Model 737-200 series aircraft in the web of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord. An 11 inch crack was found on an aircraft with 40,000 total flight cycles, and a 3.5 inch crack was found on an aircraft with 28,000 total flight cycles. Such fatigue cracking, if not detected and corrected, could result in rapid decompression of the fuselage.