Summary
The FAA is revising an earlier proposed airworthiness directive (AD) for certain Learjet Model 45 airplanes. The original NPRM would have required revising the Airworthiness Limitations section of the airplane maintenance manual to incorporate certain inspections and compliance times to detect fatigue cracking of certain principal structural elements (PSEs). The original NPRM resulted from new and more restrictive life limits and inspection intervals for certain PSEs. This action revises the original NPRM by changing the applicability to add certain airplanes. We are proposing this supplemental NPRM to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.