Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all McDonnell Douglas Model MD-90- 30 airplanes. This proposal would require revising the Airworthiness Limitations Section of the Instructions for Continued Airworthiness [MD-90-30 Airworthiness Limitations Instructions (ALI)]. The revision would incorporate certain compliance times for inspections to detect fatigue cracking of principal structural elements (PSE) and to add PSE's to the ALI. This proposal is prompted by analysis of data that identified reduced initial inspection thresholds, reduced repetitive inspection intervals for PSE's, and other PSE's to be added to the ALI. The actions specified by the proposed AD are intended to ensure that fatigue cracking of various PSE's are detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.