For Immediate Release

Release No. APA 126-98
October 8, 1998
Contact: Alison Duquette
Phone: 202-267-8521


WASHINGTON, DC — The Federal Aviation Administration (FAA) today issued a Notice of Proposed Rulemaking (NPRM) Airworthiness Directive (AD) to order inspections of some Boeing 737s to detect and repair fatigue cracks on the forward pressure bulkhead. The proposed AD is prompted by reports of structural fatigue cracks in the fuselage bulkhead that could result in rapid decompression of the aircraft.

Fatigue cracks on 737s have been found in three bulkhead areas: the side chord, vertical chord, and on the bulkhead web. These pressure bulkheads are located just forward of the flight deck.

The AD will apply to Boeing 737-100, -200, -300, -400, and -500 series aircraft. The agency proposes that those aircraft with 60,000 or more total flight cycles be inspected within 1,500 flight cycles. Aircraft with less than 60,000 total flight cycles would receive initial inspection prior to the accumulation of 15,000 total flight cycles or within 3,000 flight cycles, whichever occurs later. All aircraft would then undergo repetitive inspections every 3,000 cycles.

In addition, the AD requires operators to modify the bulkhead prior to the accumulation of 75,000 total flight cycles or within 12,000 flight cycles, whichever occurs later. The modifications consist of replacing portions of the bulkhead center web area and installing certain angles and straps to strengthen the side and vertical chord areas. These modifications would eliminate the need for repetitive inspections on some bulkhead areas.

Worldwide, there are 2,802 Boeing 737s affected by this AD. Of those, 1,130 aircraft are registered in the United States. The total cost to U.S. operators would be approximately $26 million per inspection cycle, $23,000 per aircraft. The preventative modification work that would eliminate a need for inspections would cost a total of approximately $71 million, $63,000 per aircraft. Most major U.S. airlines operate these aircraft.

Comments are due to the FAA within 45 days. Depending on the volume of comments and the issues raised, the FAA expects to have a final rule AD in early 1999.

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