Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 777 airplanes. This proposed AD was prompted by four reports of retaining cross bolt hardware not fully engaged into the fuse pins of the forward trunnion lower housing of the main landing gear (MLG), which could result in an incorrect MLG emergency landing break-away sequence. This proposed AD would require a detailed inspection of the fuse pin cross bolts and fuse pins of the left and right MLG forward trunnion lower housing to verify that the cross bolts are correctly installed and that there are no missing fuse pins, and replacement of the fuse pins if necessary. We are proposing this AD to prevent an incorrect emergency landing MLG break-away sequence, which could result in puncturing of the wing box and consequent fuel leaks and an airplane fire. Failure of the fuse pins could also result in a premature landing gear collapse causing a runway excursion during take- off or landing.