Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 737-400 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) which indicates that the aft fuselage skin is subject to widespread fatigue damage (WFD) and reports of aft fuselage skin cracking. This proposed AD would require repetitive inspections to detect cracking of the aft fuselage skin, inspections to detect missing or loose fasteners and any disbonding or cracking of bonded doublers, permanent repairs of time- limited repairs, related investigative and corrective actions if necessary, and skin panel replacement. We are proposing this AD to detect and correct cracking in the aft fuselage skin along the longitudinal edges of the bonded skin doubler, which could result in possible rapid decompression and reduced structural integrity of the airplane.