Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 737-300, -400, and -500 series airplanes. This proposed AD would require revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating for each structural significant item (SSI), doing repetitive inspections to detect cracks of all SSIs, and repairing cracked structure. This proposed AD results from a report of incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design service objective. We are proposing this AD to maintain the continued structural integrity of the entire fleet of Model 737-300, -400, and - 500 series airplanes.