Airworthiness Directives; The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

요약

We propose to supersede an existing airworthiness directive (AD) that applies to certain Model 737-100 and -200 series airplanes. The existing AD currently requires various inspections for cracks in the outboard chord of the frame at body station (BS) 727 and in the outboard chord of stringer (S) 18A, and repair or replacement of cracked parts. Since we issued that AD, there have been several reports of fatigue cracking in the frame outboard chord at BS 727 and in the radius of the auxiliary chord on airplanes that were not affected by the existing AD. This proposed AD would add airplanes to the applicability statement in the existing AD and add inspections for cracks in the BS 727 frame outboard chords and the radius of the auxiliary chord, for certain airplanes. This proposed AD would also remove the inspections of the outboard chord of S-18A required by the existing AD. We are proposing this AD to detect and correct fatigue cracking of the outboard and auxiliary chords, which could result in reduced structural integrity of the outboard chord and consequent rapid decompression of the airplane.