Airworthiness Directives; Boeing Model 727 Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 727 airplanes. This AD requires a one-time inspection of the lower lobe frames of body section 43 to find open holes between stringers 17L and 17R and to record their location; repetitive high frequency eddy current (HFEC) inspections for cracks of all open holes; and related investigative and corrective actions if necessary. This AD also includes an optional terminating action of installing rivets in all open tooling holes and all unused lining holes, which would terminate the repetitive open-hole HFEC inspections once a hole is plugged with a rivet. This AD results from reports of cracks at open tooling holes in the lower lobe frames of body section 43. We are issuing this AD to detect and correct cracks in the frames, which could result in cracks in the skin panels and rapid decompression of the airplane.