Summary
We propose to supersede Airworthiness Directive (AD) 2007-26- 04, which applies to certain Boeing Model 737-100, -200, -200C, -300, - 400, and -500 series airplanes. AD 2007-26-04 currently requires repetitive inspections for cracking around the heads of the fasteners on the forward fastener row of certain areas of a certain circumferential butt splice, and repair if necessary; and also requires a preventive modification, which eliminates the need for the repetitive inspections. Since we issued AD 2007-26-04, an evaluation by the design approval holder (DAH) indicating that the forward skin panel at a circumferential butt splice between certain stringers is subject to widespread fatigue damage (WFD). This proposed AD would remove the mandatory modification. It would add repetitive inspections of the skin for cracking at the aft fastener column and a one-time inspection for defects of the production countersunk rivets, and require corrective actions if necessary. It would alsoadd an optional skin trim-out repair, which would terminate certain inspections. We are proposing this AD to prevent cracking of the station (STA) 259.5 circumferential butt splice, which could result in loss of structural integrity of the fuselage skin and possible loss of cabin pressure.