AD FAA-2012-0998

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