Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This proposed AD was prompted by a new revision to the airworthiness limitations of the maintenance planning data document. This proposed AD would require revising the maintenance program to update inspection requirements to detect fatigue cracking of principal structural elements (PSEs). We are proposing this AD to detect and correct fatigue cracking of various PSEs, which could adversely affect the structural integrity of these airplanes.