Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede Airworthiness Directive (AD) 95-26-11, which applies to all Lockheed Martin Corporation/Lockheed Martin Aeronautics Company Model L-1011 series airplanes. AD 95-26-11 currently requires inspections to detect cracking of the fittings that attach the aft pressure bulkhead to the fuselage stringers, inspections to detect cracking of the fittings and of the splice tab of the aft pressure bulkhead, and corrective actions if necessary. Since we issued AD 95-26-11, we have determined that the fittings at stringer attachments to the upper region of the aft pressure bulkhead are subject to widespread fatigue damage (WFD), which could result in cracking in the aft pressure bulkhead. This proposed AD would reduce the compliance time; add inspections for cracking of certain aft fuselage skin panels; add a structural modification; and also add a post modification inspection program. We are proposing this AD to prevent simultaneous failure of multiple stringer end fittings through fatigue cracking at the aft pressure bulkhead, which could lead to rapid decompression of the airplane.