WASHINGTON (Army News Service, Nov. 8, 1999) -- The Army announced Nov. 5 that its Apache helicopters must undergo a one-time inspection before the aircraft can fly, due to possible problems with a hanger bearing assembly.
The assembly to be inspected is part of the tail rotor system. The failure of a basic configuration hanger bearing assembly reportedly caused the crash of an aircraft at Fort Rucker, Ala., earlier this year. The accident resulted in only minor injuries to the two-man crew
Preliminary indications are that hydrogen embrittlement, a hardness heat-treat process, may have caused stress corrosion fractures in the hangar bearing assembly, officials said.
Hanger bearing assemblies produced after 1993 do not have the potential for stress corrosion fractures, officials said, because the manufacturing process changed that year.
An inspection of all 743 AH-64 aircraft (both AH-64 "A" and "D" models) will be performed to determine if the suspect hanger bearing assemblies are installed. If they are, they will be replaced. Aircraft with non-suspect hanger bearing assemblies will be returned to flight status immediately.
This inspection, which takes about an hour, is to take place as soon as practical, but prior to the aircraft's next flight and no later than one week from notification, officials said.
The Army stated it anticipates no problems with readiness because of the inspections. While some aircraft will be grounded for hanger bearing assembly replacement, officials said, other training and maintenance activities will continue and the Army will work to get its priority, first-to-fight units returned to flight.
The Army is working with the hanger bearing assembly contractor, Boeing, to ensure that adequate replacement assemblies are manufactured and supplied to the fleet, officials said. They said it is an Army-Industry team effort to return the Apaches to flight operations as quickly as possible.
(EDITOR'S NOTE: Information provided by a HQDA Public Affairs news release.)