Action
Final rule.
Summary
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 777 airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the lap splices of the aft pressure bulkhead webs are subject to widespread fatigue damage (WFD) on aging Model 777 airplanes that have accumulated at least 38,000 total flight cycles. This AD requires repetitive inspections for any crack in the aft webs of the radial lap splices of the aft pressure bulkhead, and, if necessary, corrective actions. We are issuing this AD to detect and correct fatigue cracking in the aft webs of the radial lap splices of the aft pressure bulkhead; such cracking could result in reduced structural integrity of the airplane, decompression of the cabin, and collapse of the floor structure.