Summary
We propose to supersede Airworthiness Directive (AD) 2002-07- 08, which applies to certain The Boeing Company Model 737 airplanes. AD 2002-07-08 currently requires repetitive inspections for cracking of the lower skin at the lower row of fasteners in the lap joints of the fuselage; repair of any cracking found; modification of the fuselage lap joints at certain locations, which terminates the repetitive inspections of the modified areas; and replacement of a certain preventive modification with an improved modification. Since we issued AD 2002-07-08, we have determined that adjacent stringers and window frames have cracked in locations outside the inspection areas addressed by AD 2002-07-08. This proposed AD would add repetitive inspections for cracking at certain window corner fastener holes, a preventive modification, post-repair/alteration and butt joint repetitive inspections, and repair if necessary. We are proposing this AD to detect and correct fatigue cracking of the fuselage lap joints, which could result in reduced structural integrity and sudden decompression of the airplane.