The Army announced Friday that it had grounded its fleet of Boeing CH-47D transport helicopters for safety inspections, one day after congressional investigators attacked alleged design problems in another type of Army helicopter.
It was the second grounding of the CH-47s in eight months, this time for inspection of nuts used to lock the engine transmission to the frame. The Army said some cracked nuts were found during recent routine maintenance.
The Army has experienced problems with a wide range of helicopters in the past two years and the Pentagon is now deciding whether to go ahead with a new multibillion-dollar program of light utility and scout helicopters.
The General Accounting Office reported at a House hearing Thursday that the AH-64 Apache attack helicopters made by McDonnell Douglas Corp. had serious problems with rotor blades and malfunctioning electronic equipment.
The GAO recommended that the Apache force be limited to 675 aircraft purchased or under contract instead of the proposed $12 billion fleet of 807, and that plans to upgrade the helicopter be deferred until the Army has dealt with problems in maintaining them.
The CH-47D is produced by the Boeing-Vertol division of Boeing Co.
The Army said it had ordered the grounding of all 290 helicopters in the fleet "because cracks have been found in the barrel nuts associated with the aircraft's forward transmission." Four of the nuts are used to secure the transmission to the body of the helicopter.
The cracked nuts were discovered recently while being replaced on a CH-47D undergoing a normal maintenance operation.
The Army said approximately 300 of the suspect barrel nuts were in the service's inventory and that the helicopters would be allowed to fly until the four nuts on each had been inspected.