Summary
We propose to adopt a new airworthiness directive (AD) for certain Model 727 airplanes. This proposed AD would require inspections for scribe lines in the fuselage skin at skin lap joints and butt joints, the skin at certain external approved repairs, the skin around external features such as antennas, and the skin at decals and fairings; and related investigative and corrective actions if necessary. This proposed AD results from reports of scribe lines found at skin lap joints and butt joints, around external repairs and antennas, and at locations where external decals had been cut. We are proposing this AD to detect and correct scribe lines, which can develop into fatigue cracks in the skin and cause rapid decompression of the airplane.