Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 757 series airplanes. The existing AD currently requires revising the Airworthiness Limitations Section of the maintenance manual (757 Airworthiness Limitations Instructions (ALI)) to incorporate certain inspections and compliance times to detect fatigue cracking of principal structural elements (PSEs). This proposed AD would require incorporating a new revision to the Airworthiness Limitations section of the Instructions of Continued Airworthiness to mandate certain repetitive inspections for fatigue cracking of PSEs. This proposed AD also would add airplanes to the applicability in the existing AD. This proposed AD results from a new revision to the ALI. We are proposing this AD to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.