Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-500 series airplanes. This proposed AD was prompted by reports of chem-mill step cracking on the aft lower lobe fuselage skins. This proposed AD would require inspections of the fuselage skin at the chem-mill steps, and repair if necessary. We are proposing this AD to detect and correct cracking on the aft lower lobe fuselage skins, which could result in decompression of the airplane.