Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposed AD was prompted by a report of cracks in stringer splices at body station STA 360 and STA 908, between stringer (S) S-10L and S-10R; cracks in butt straps between S-5L and S- 3L, and S-3R and S-5R; vertical chem-mill fuselage skin cracks at certain butt joints; and an instance of cracking that occurred in all those three structural elements on one airplane. This proposed AD would require repetitive inspections for any cracking of stringer splices and butt straps, and related corrective and investigative actions if necessary. We are proposing this AD to detect and correct cracking in the three structural elements, which could result in the airplane not being able to sustain limit load requirements and possibly result in uncontrolled decompression.