Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede Airworthiness Directive (AD) 2011-01- 15, which applies to certain The Boeing Company Model 757-200, -200CB, and -300 series airplanes. AD 2011-01-15 currently requires repetitive inspections for cracking of the fuselage skin of the crown skin panel along the chem-milled step at stringers S-4L (left) and S-4R (right), from stations (STA) 297 through STA 439, and repair, if necessary. AD 2011-01-15 also includes terminating action for the repetitive inspections of the repaired areas only. Since we issued AD 2011-01-15, we received reports of the initiation of new fatigue cracking in the fuselage skin of the crown skin panel along locally thinned channels adjacent to the chem-milled steps. This proposed AD would add repetitive inspections for cracking in additional areas and repair if necessary. This proposed AD would also remove airplanes from the applicability in AD 2011-01-15. This proposed AD would also add an optional skin panel replacement which would terminate all inspections and an optional preventative modification that would terminate certain inspections. We are proposing this AD to detect and correct fatigue cracking of the fuselage skin of the crown skin panel, which could result in pressure venting and consequent rapid decompression of the airplane.