San Diego Union-Tribune


15-Feb-2001 Thursday 

Increase in checks of copters ordered
Metal wear problem prompts mandate 


WASHINGTON -- The Navy and Marine Corps have ordered more frequent inspections of their CH-46E helicopters because of a metal fatigue problem with a key component of their rotor systems.

The order affects 129 of the aging Sea Knights that are based in San Diego County.

The Naval Aviation Systems Command ordered all Navy and Marine units to inspect the rotor heads of their CH-46s every 10 hours to check for cracks in a component that controls the pitch of the forward rotors on the twin-rotor helicopters.

The inspection time was cut from every 25 hours after the discovery Feb. 1 of a crack in the forward longitudinal differential bellcrank on a Navy Sea
Knight. It was the third such crack discovered on an CH-46.

Although a failure of the bellcrank would result in a loss of control of the craft, there have been no Sea Knight accidents attributed to such a failure, both services said yesterday.

The inspection takes about 30 minutes and requires a spreading of the rotor blades.

That "poses particular challenges aboard ship," the Marines said, because the blades usually are folded once a helicopter has landed due to the limited space.

The order affects all 308 CH-46s in the naval services. That includes 50 at Miramar Marine Corps Air Station, 44 at Camp Pendleton and 35 at North Island Naval Air Station.

The Marines hope to replace the Vietnam War-vintage CH-46s with the MV-22 Osprey. But production of the tilt-rotor aircraft has been stalled by fatal accidents.