Summary
We propose to supersede Airworthiness Directive (AD) 2011-09- 11, which applies to certain The Boeing Company Model 777-200 and -300 series airplanes. AD 2011-09-11 currently requires repetitive inspections for hydraulic fluid contamination of the interior of the strut disconnect assembly; repetitive inspections for discrepancies of the interior of the strut disconnect assembly, if necessary; repetitive inspections of the exterior of the strut disconnect assembly for cracks, if necessary; corrective action if necessary; and an optional terminating action for the inspections. Since we issued AD 2011-09-11, we have received reports of side and top cover plates installed with missing fastener bolts, which results in an unsealed opening on the system disconnect assembly. This proposed AD would add, for certain airplanes, an inspection of the side and top cover plates to determine if all cover plate attach fasteners have been installed, and installing any missing fasteners including doing an inspection for damage, and repair if necessary. We are proposing this AD to detect and correct hydraulic fluid contamination, which can cause cracking of titanium parts in the system disconnect assembly; and also to detect and correct missing fasteners, which results in unsealed openings on the system disconnect assembly. Both unsafe conditions can compromise the engine firewall and result in fire hazards for both the engine compartment and the strut.