Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 727 airplanes. This proposed AD would require a one-time inspection of the lower lobe frames of body section 43 to find open holes between stringers 17L and 17R; repetitive high frequency eddy current (HFEC) inspections for cracks of all open holes; and related investigative and corrective actions if necessary. The proposed AD also would include the optional terminating action of installing rivets in all open tooling holes and all unused lining holes, which would terminate a repetitive open-hole HFEC inspection once a hole is plugged with a rivet. This proposed AD is prompted by reports of cracks at open tooling holes in the lower lobe frames of body section 43. We are proposing 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.