The U.S. Army and National Guard have grounded their fleets of UH-1 Huey helicopters, which have an unexplained history of potentially catastrophic mechanical problems.
The military has placed wide restrictions on the Vietnam-era helicopters since November - including barring flights in clouds and over water - but declared Hueys safe to fly as recently as last week.
On Friday, military officials changed their minds.
“After careful consideration and as a prudent measure of safety, the Army is grounding its fleet of UH-1 helicopters until each helicopter engine can be tested to determine if there are excessive vibrations,” Bob Hunt, spokesman for the Army Aviation Missile Command at Redstone, Ala., told the Boston Globe in Sunday’s editions.
In all, 907 Huey helicopters are expected to be grounded for between six months and two years. The majority of those are used by the National Guard.
Hunt said the National Guard has about 400 newer UH-60 Black Hawk helicopters to offset the impact of grounding the Hueys, which went out of production in the mid-1970s.
Gearbox problems in the Hueys were blamed for some near disasters last year. Pilots reported the engines would speed up while gauges dropped to zero.
The Army still has not found the cause. According to an internal review, 22 “mishaps” related to the gearbox were reported in the last two years. None resulted in death.