Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 707 and 720 series airplanes. This proposal would require repetitive inspections of the upper and lower barrel nuts and bolts that retain the aft trunnion support fitting of each main landing gear for corrosion, cracks, and loose or missing nuts and bolts; torque checks of the upper and lower bolts to verify the torque is within a specified range; and corrective actions, if necessary. This action is necessary to detect and correct cracking and/or loss of the barrel nuts and bolts that retain the aft trunnion support fitting, which could result in the collapse of the main landing gear upon landing. This action is intended to address the identified unsafe condition.