Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes. This proposed AD was prompted by reports of fatigue cracking of a certain chord of the pivot bulkhead. This proposed AD would require repetitive inspections for cracking of the left side and right side forward outer chords of the pivot bulkhead, and related investigative and corrective actions if necessary. This proposed AD provides a modification of the pivot bulkhead, which would terminate the repetitive inspections. We are proposing this AD to detect and correct fatigue cracking of the outer flanges of the left and right side forward outer chords of the pivot bulkhead, which could result in a severed forward outer chord and consequent loss of horizontal stabilizer control.