Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD requires various repetitive inspections for cracking of the upper frame to side frame splice of the fuselage, and other specified and corrective actions if necessary. This AD also provides for an optional preventive modification, which terminates the repetitive inspections. This AD results from a report that the upper frame of the fuselage was severed between stringers S-13L and S-14L at station 747, and the adjacent frame at station 767 had a 1.3-inch-long crack at the same stringer location. We are issuing this AD to detect and correct fatigue cracking of the upper frame to side frame splice of the fuselage, which could result in reduced structural integrity of the frame and adjacent lap joint. This reduced structural integrity can increase loading in the fuselage skin, which will accelerate skin crack growth and result in decompression of the airplane.