Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 747-100, 747- 100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes. The existing AD currently requires repetitive inspections to find cracking of the web, strap, inner chords, inner chord angle of the forward edge frame of the number 5 main entry door cutouts, the frame segment between stringers 16 and 31, and repair if necessary; and repetitive inspections for cracking of repairs. Since we issued that AD, we have received multiple reports of cracking outside of the previous fuselage inspection areas and a report of a crack that initiated at the aft edge of the inner chord rather than initiating at a fastener location, which was the previous cracking location. This proposed AD would expand the previous fuselage areas that are inspected for cracking. We are proposing this AD to detect and correct such cracks, which could cause damage to the adjacent body structure and could result in depressurization of the airplane in flight.