FARNBOROUGH, England – The Marines Corps top aviator confirmed the service still isn’t sure what caused an MV-22 Osprey engine problem in Iraq last month that precautionary landing well away from the base.
In response to questions at the Farnborough Air Show, Lt. Gen. George Trautman III, Marine deputy commandant for aviation, said the pilot “did a fantastic job” of bringing the heavily loaded aircraft to a safe landing in the June 21 incident.
The incident, first reported on the Fort Worth Star-Telegram’s Sky Talk blog, occurred shortly after the aircraft took off with 20 Marines and a full load of fuel. According to an internal Marine memorandum, the pilots found the right hand engine on the aircraft would only generate about 60 percent power and were unable to maintain altitude, even though the second engine was performing normally.
Trautman said the flight crew decided to make a “precautionary landing in a field” and were able to hover in ground effect and make a vertical landing. Trautman said temperatures in the region were about 40 degree Celsius (104 Fahrenheit).
The incident raises questions about why the pilot didn’t simply return to base. The V-22, once airborne and flying in airplane mode, is required to be able to fly after the loss of power in one engine.
An interconnecting drive shaft links the two prop-rotors on the aircraft. In the worst case, if a pilot is unable to hover after loss of an engine -- which could prove impossible depending on the weight of the aircraft, temperature and altitude--- the pilot could make an emergency run-on landing in airplane mode.
According to the internal memorandum, an inspection showed possible foreign damage to the compressor blades. But there was also an indication that the combustion liner was breaking up and pieces had further damaged other engine parts.
But Trautman said further examination had not pinpointed the cause of the engine trouble. Trautman downplayed reports that the Marines were unhappy with the reliability of the Allison/Rolls Royce turbine engines, saying they were performing about as well in the heat and dust of Iraq as other helicopter engines. -By Bob Cox