Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 737-300 and 737-400 series airplanes. This proposed AD would require repetitive inspections to detect cracking of the aft fuselage skin, and related investigative/corrective actions if necessary. This proposed AD results from reports of cracks in the aft fuselage skin on both sides of the airplane. 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 reduced structural integrity of the airplane.