Summary
We are revising an earlier proposal to supersede Airworthiness Directive (AD) 2008-13-12 R1, for certain The Boeing Company Model 737- 100, -200, -200C, -300, -400, and -500 series airplanes. AD 2008-13-12 R1 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; and also provides for an optional preventive modification, which would terminate the repetitive inspections. This action revises the notice of proposed rulemaking (NPRM) by adding post-repair/post-modification inspections. We are proposing this SNPRM 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, causing increased loading in the fuselage skin, which will accelerate skin crack growth and result in decompression of the airplane. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.