AD FAA-2017-0774

We are superseding Airworthiness Directive (AD) 2012-12-05, which applied to all The Boeing Company Model 737-100, -200, -200C, - 300, -400, and -500 series airplanes. AD 2012-12-05 required repetitive inspections for cracking under the stop fittings and intercostal flanges and for cracking of the intercostal web, attachment clips, stringer splice channels, frame, reinforcement angle, shear web, frame outer chord and inner chord; a one-time inspection to detect missing fasteners; repetitive inspections of the cargo barrier net fitting for cracking; repetitive inspections for cracking of the stringer S-15L aft intercostal; and repair or corrective action if necessary. For certain airplanes, this AD adds new repetitive inspections of certain areas of the frame inner chord, and applicable on-condition actions. This AD was prompted by reports of additional cracking in locations not covered by the inspections in AD 2012-12-05. We are issuing this AD to address the unsafe condition on these products.