By Kentaro Nakajima, The Yomiuri Shimbun –
WASHINGTON — The U.S. Marine Corps said Friday its investigation into an MV-22 Osprey crash in Morocco earlier this year found no mechanical problems with the new transport aircraft.
The U.S. military plans to deploy the aircraft in Okinawa Prefecture, Japan, but the crash has fueled concerns in Japan about its safety.
In its final investigative report, the Marine Corps concluded the crash was caused mainly by a strong tailwind and the pilots’ failure to follow flight procedures. The aircraft crashed on April 11 after transporting Marines who were participating in a joint military exercise with Moroccan forces to a landing zone.
According to the report, the pilots lifted off in the Osprey and started making a 180-degree turn about six meters (about 20 feet) off the ground. The pilots then moved forward the rotors, which had been straight up, to make the aircraft fly like a plane.
The flight manual for the MV-22 states that pilots must keep the fuselage level when the aircraft’s rotors are being shifted. However, the pilots were not aware that the aircraft was tilted forward due to a strong wind.
The aircraft also exceeded the manual’s limits on airspeed and the angle of the rotors. The pilots placed the aircraft into a tailwind of about 30 to 50 kph (18.6 to 30 mph). This moved the plane’s center of gravity forward, pushing the nose farther down. As a result, the aircraft crashed. The report ruled out mechanical faults because no problems were reported when another pilot flew the aircraft shortly before the crash. It also said all required maintenance was conducted on the aircraft and it was considered safe for flight.
Following the investigation, the Marine Corps said it will implement measures to prevent similar incidents, such as revising the flight operation manual and improving simulation training.
“There were no safety issues with the aircraft,” Marine Corps Lt. Gen. Robert Schmidle said at a press conference Friday. “It’s an extraordinarily complex set of circumstances that caused this to happen.”
