HONOLULU (AP) — A hybrid aircraft that crashed in Hawaii this year, killing two , flew in sandy or dusty conditions for an extended period before its engine stalled, theU.S. Corps said Monday.
An investigation found the stalled left engine put the MV-22 Osprey in an unavoidable freefall, U.S. Corps Forces, Pacific said in a news release.
The airplane-and-helicopter hybrid crashed at a base outside Honolulu in May with 21 and a corpsman on board.
The pilots didn’t violate any regulations or flight standards, the said. But investigators found a proper risk assessment should have prompted the pilots to choose a different flight path or landing site to avoid dust or sand.
Investigators have recommended changes to help pilots make better decisions in similar situations.
One is to have the Osprey display engine performance and stall data. Another is to have the aircraft alert pilots when engine power declines below 95 percent. Investigators also want the to improve the MV-22’s engine air filtration systems.
The has already made an interim change to training and operating procedures as a result of the accident, the Corps said.
The Osprey is a tilt-rotor aircraft that can take off and land like a helicopter but flies like an airplane, which gives it a longer range than traditional helicopters.
The Osprey that crashed took off from the USS Essex, a ship 100 miles offshore. It was en route to drop off infantry for training when it crashed at Bellows Station on Oahu’seastern coast.
The aircraft was part of the 15th Expeditionary Unit based in Camp Pendleton, California. It was visiting Hawaii for a week of training during a seven-month deployment to the Pacific and theMiddle East.
The crash killed Lance Cpl. Matthew Determan, 21, of Ahwatukee, Arizona and Lance Cpl. Joshua Barron, 24, of Spokane, Washington.