Summary
We propose to adopt a new airworthiness directive (AD) for all the Boeing Company Model 727 airplanes. This proposed AD is intended to complete certain mandated programs intended to support the airplane reaching its limit of validity (LOV) of the engineering data that support the established structural maintenance program. This proposed AD would require repetitive inspections for cracking of small repairs done on the vertical flange of the rib chord, repetitive inspections for cracking along the upper fillet radius of the rib chord, and a large repair or preventive modification if necessary. Accomplishment of a large repair or preventive modification would terminate the actions of the proposed AD. We are proposing this AD to prevent cracks in the rib upper chord, which could result in the inability of the wing structure to support the limit load condition, and consequent loss of structural integrity of the wing.