Airworthiness Directives; Boeing Model 757 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 757 series airplanes, that requires revising the Airworthiness Limitations Section of the maintenance manual (757 Airworthiness Limitations Instructions (ALI)). The revision will incorporate into the ALI certain inspections and compliance times to detect fatigue cracking of principal structural elements (PSE). This amendment is prompted by analysis of data that identified specific initial inspection thresholds and repetitive inspection intervals for certain PSEs to be added to the ALI. The actions specified by the proposed AD are intended to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.