ARLINGTON, Va. — A new government study released Tuesday blasts the reliability, performance and cost of the controversial V-22 Osprey, the iconic tilt-rotor aircraft plagued by problems throughout its 20-year lifespan.

In response to the new data, and performance updates provided by the Pentagon, the chairman of the House Oversight Committee called for the entire Osprey production line to be suspended.

“To sum up, it has problems in hot weather, it has problems in cold weather, it has problems with sand, it has problems with high altitude, and it has restricted maneuverability,” said Rep. Edolphus “Ed” Towns, D-NY, in a hearing with the Marine Corps’ aviation commander on Tuesday. “The list of what the Osprey can’t do is longer than the list of what it can do. It’s time to put the Osprey out of its misery.”

The latest report on the Osprey by the Government Accountability Office comes in the middle of a Pentagon effort to train and deploy more helicopters and crews for the buildup of American forces in Afghanistan.

The hearing was postponed a month after Towns and Republican ranking member Darrell Issa of California asked the Pentagon for a progress report on the combat readiness of the Osprey fleet.

The results, Towns said, were “surprising and appalling.” Only 47 of the 105 Ospreys purchased since 1988 are “combat deployable,” the Pentagon had told Congress. At one point in June, the Marine Corps found just 23 were ready for combat.

Lt. Gen. George J. Trautman III, the Marine Corps’ deputy commandant for aviation, conceded much of the GAO’s contentions but defended the Osprey’s capabilities and rejected calls for the Navy to seek alternatives for the Osprey program. He said the data used to criticize its performance came from just a dozen of the most heavily used aircraft.

The general characterized the Osprey issues as unsurprising growing pains of a vehicle never before tested at such high tempos or harsh conditions. Though he admitted breakdowns have been a problem, he said the third Osprey squadron to fly in Iraq recently returned with “highly successful” results after seven months.

“This aircraft is effective and suitable. It is the future of Marine Corps assault support,” said Trautman. “The MV-22B has done exactly what we have asked it to do, and more.”

The government’s internal watchdog group says Ospreys, when working, generally have performed well in Iraq under “low-threat environments” and that its speed and range “cut the battlefield in half.” But problems that arose in Iraq — including engine parts lasting a “fraction” of their expected life and a broken supply chain — have pushed the numbers of Osprey available to U.S. forces “significantly below minimum required levels,” the GAO said.

“Based on the Iraq experience, the cost per flight hour is more than double the target estimate,” the report concluded.

The overall cost per aircraft has tripled since its original inception, Towns said, to $120 million each.

If Ospreys protected troops as intended, Towns said he would support it.

“But at $120 million per aircraft—the Osprey better work as advertised,” he said.

In the fiscal 2010 budget, the Pentagon is requesting $2.3 billion to buy another 30 V-22B aircraft, toward a final goal of 360 Ospreys.

“However, questions have arisen about whether the MV-22” — the Marine Corps version — “is the aircraft best suited to accomplish the full mission repertoire of the helicopters it is intended to replace, and some challenges in operational effectiveness have been noted,” the report said, faulting a backlog in the supply chain of badly needed spare parts.

Retired Lt. Col Daniel J. Sullivan was the wing supply officer of the 2nd Marine Aircraft Wing at Marine Corps Air Station Cherry Point in North Carolina from 2004 to 2008. He said his team intimately was aware of the parts and engineering reliability problems facing the aircraft and put in a “monumental effort” to get the Ospreys ready for war, with little oversight about the expense.

“We were battling to get the aircraft down to within reasonable costs,” said Sullivan. But once they began to ready Ospreys for war, he said, “There was not a whole sense of urgency on keeping it within the projected cost limitations early on.”

Sullivan, who was in charge of the 2nd MAW’s entire aircraft fleet, said the Osprey monopolized his time.

“I probably spent 90 percent of my time and effort dealing with problems associated with the MV-22,” he said. “We were plagued with serious issues: engineering-related, reliability related, [and] with the parts. We were on daily teleconferences with program management and the manufacturers regarding even the minutest of details.”

Richard Whittle, a longtime Pentagon reporter for Dallas Morning-News, is writing a book on the Osprey to be published next spring. He said it is about “the dream of the perfect aircraft, and how the Marines got sold on that dream, and why they were so determined to have it they were willing to spend 25 years and $22 billion to get it.”

“The V-22 is more expensive than the Marines would want it to be,” he said, “but they still feel they’re going to get so much more out of it than a helicopter offers that they’re willing to pay that price.”

Whittle rode along with Marines on a V-22 mission in 2007 in Anbar and can testify to its speed.

“Afghanistan is going be a real test,” he said. “I think the jury’s still out.”

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