Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 727 airplanes. This proposed AD was prompted by reports of spanwise cracks and corrosion in the wing center box upper skin and rear spar upper chord between left buttock line (LBL) 70.50 and right buttock line (RBL) 70.50 at body station (STA) 870. This proposed AD would require repetitive inspections of the wing center box for cracking around certain fastener rows on the rear spar upper chord horizontal flange; for certain airplanes, repetitive inspections for cracking of the rear spar upper chord radius; for certain other airplanes, repetitive inspections for damage, cracking, and corrosion of the pressure seal; and repair if necessary. We are proposing this AD to detect and correct cracking and corrosion of the upper skin and rear spar upper chord of the wing center box, which could result in loss of the airplane wing and consequent loss of control of the airplane.