Defect Grounds Vietnam-Era Helicopter

Age has caught up with one of the military’s most storied helicopters.

A crack found in a rotor component of the Vietnam-era CH-46 Sea Knight has led the Navy and Marine Corps to ground the entire fleet, including 45 on duty overseas, officials said Wednesday.

Ward Carroll, a spokesman for Naval Air Systems Command, said the temporary grounding was a precautionary move after the discovery during a routine inspection of a crack in the rotor assembly on a craft at Marine Corps Air Station Cherry Point in North Carolina.

As of Wednesday, about half the 291 Sea Knights in the fleet had been inspected for the same defect and only one more was found, Carroll said. Those cleared by inspection are immediately returned to service.

By itself, the problem is not a major setback for Navy and Marine Corps aviation. But it is the latest in a series of mechanical troubles for the Sea Knight, and is symptomatic of the problems affecting many aging military aircraft. The problems also make it more expensive to keep the aircraft in service.

The Sea Knight, which has been flying 38 years, has to be inspected more frequently for mechanical flaws, and the Marine Corps’ version is limited to carrying 12 troops instead of the 25 as originally designed. The Marines say the cost per flight hour has risen 75% in recent years.

Similar problems face the Air Force’s C-5 transport, the Navy’s F-14 Tomcat fighter and EA-6B electronic warfare plane, and the Army’s AH-64 Apache copter.

The Marine Corps relies on the Sea Knight as its primary combat assault helicopter. The Navy uses it to ferry equipment. Built by Boeing Co., the Sea Knight entered service in June 1964, making it older than most of the personnel who now fly it.