Airworthiness Directive · Amendment 39-9799 · The Boeing Company Airplanes
The Boeing Company Airplanes
This AD applies to The Boeing Company 737-100 Series, 737-200 Series, 737-200C Series, 747-100 Series, 747-100B Series, 747-100B SUD Series, 747-200B Series, 747-200C Series, 747-200F Series, 747-300 Series, 747SP Series.
The models as the FAA's AD index lists them. The serial ranges, installed parts and exceptions are in the AD itself: read it at the FAA.
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737 and 747 series airplanes, that requires replacement of Waterman hydraulic fuse assemblies with modified assemblies. This amendment is prompted by reports of failure of hydraulic system A and the standby system, due to corrosion on the magnesium piston of the hydraulic fuse and consequent failure of the fuse to close sufficiently to prevent the loss of hydraulic fluid from the system. The actions specified by this AD are intended to prevent such failure of the fuse, which could result in the failure of one or more hydraulic systems and resultant reduced controllability of the airplane.
