Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 737-100, -200, - 200C, -300, -400, and -500 series airplanes. The existing AD currently requires repetitive inspections of the intercostal webs, attachment clips, and stringer splice channels for cracks; and corrective action if necessary. This proposed AD would reduce the repetitive inspection intervals from 25,000 flight cycles to 6,000 flight cycles, and expand the inspection area for Model 737-200C series airplanes to include the area aft of the forward entry door. This proposed AD results from additional reports of fatigue cracks. We are proposing this AD to detect and correct fatigue cracking of the intercostals on the forward and aft sides of the forward entry door, which could result in loss of the forward entry door and rapid decompression of the airplane.