Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 737-300, -400, and -500 series airplanes. The existing AD currently requires repetitive inspections for cracking of the crown area of the fuselage skin, and corrective actions if necessary. Since we issued that AD, we received additional reports of cracking at the horizontal chem-mill steps away from the lap joints over the entire crown area, and vertical chem-mill cracks adjacent to the butt joints. This proposed AD would add repetitive inspections for cracking using different inspection methods and would inspect additional areas, and corrective actions if necessary. This proposed AD would also require additional repairs to previously repaired areas and repetitive inspections for loose fasteners and replacement if necessary in certain previously repaired areas. This proposed AD would also reduce certain compliance times and extend certain other compliance times. We are proposing this AD to detect and correct fatigue cracking of the fuselage skin, which could cause the fuselage skin to fracture and fail, and result in rapid decompression of the airplane.