V-22 land in 'airplane mode' Gee, that's a nice feature!
Fort Worth
Posted on Sat, Jul. 19, 2008
Cause of V-22 engine issue is still unclear
By BOB COX
[email protected]
FARNBOROUGH, England — The Marines Corps’ top aviator has confirmed that the service still isn’t sure what caused an engine problem in an MV-22 Osprey in Iraq last month that forced a precautionary landing well away from the base.
In remarks earlier this week 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.
The incident, first reported on star-telegram.com this week, occurred shortly after the aircraft took off June 21 with 20 Marines and a full load of fuel aboard.
According to an internal Marine memorandum, the pilots found that the right-hand engine on the tilt-rotor aircraft would only generate about 60 percent of the required power, and they were unable to maintain altitude, even though the second engine was performing at full power.
Trautman said the flight crew decided to make a "precautionary landing in a field" and were able to hover close to ground and make a vertical landing.
At the time of the mission, Trautman said, temperatures in the region were about 104 degrees.
The incident raises questions about why the pilot didn’t simply return to base. The V-22, once airborne and flying airplane mode, is required to be able to fly and maintain altitude after the complete loss of power in one engine.
An interconnecting drive shaft links the two prop-ro- tors on the aircraft so that it can be powered by one engine. 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.
Trautman said the Marines still don’t know exactly what was wrong with the engine.
According to the internal memorandum, obtained by the Star-Telegram, an inspection showed possible damage to the engine compressor blades from foreign objects. But there was also an indication that the engine combustion liner was breaking up and pieces had further damaged other engine parts.
The memo warned that the engine problem could have resulted in an accident or the aircraft being forced to land in enemy territory and the possible loss of personnel.
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.
Lt. Col. Paul Ryan, now commanding officer of VMM-263 Marine squadron, said he was pleased with the reliability of the Ospreys. Ryan said the squadron maintained about a 70 percent mission-capable rate, meaning that on average seven of its 10 aircraft was available for missions at any given time. The aircraft were operated about 65 hours per month and required less than 10 hours of maintenance for every flight hour, an indication that maintenance and repair requirements were relatively normal.
BOB COX, 817-723-7493