The cost for the Marines to fix and fly their full fleet of V-22 tiltrotors has grown by nearly two-thirds over just four years, according to a Pentagon estimate. In 2008, the Defense Department calculated the “lifetime” cost of operating 360 V-22 Osprey transports at $75 billion over roughly 30 years. Today the figure is more than $121 billion — a 61-percent increase.

The rapidly escalating bill could could not come at a worse time for the Marines and Osprey-makers Bell and Boeing. The Marines are struggling to pay for an ambitious, carefully coordinated aviation modernization plan, elements of which have begun to unravel all at the same time. And that’s not even taking into account the looming prospect of deep defense cuts.

Bell and Boeing, meanwhile, are hoping to convince the Pentagon and foreign governments to order more V-22s, providing years of work at the companies’ factory in Amarillo, Texas.

The V-22, which takes off like a helicopter but cruises like an airplane thanks to its rotating engine nacelles, has been controversial since development began nearly 30 years ago. Several early models of the Osprey crashed during testing, killing 30 people. A redesigned version, though safer, still crashes or burns at a rate far higher than the Marines like to admit.

Leaving aside its safety record, the V-22 ain’t cheap. A single Osprey costs $60 million to purchase,  plus millions more to support. For comparison, a Navy F/A-18E/F Super Hornet fighter is actually slightly cheaper to buy. And the Army’s workhorse UH-60 Blackhawk chopper can be had for around $15 million apiece.

The price increase should come as no surprise to close observers of the Osprey’s tortured development. In order to make up for its small wings and rotors, which are sized to fit on Navy assault ships, designers fitted the V-22 with unusually powerful Rolls-Royce engines. They run hotter than normal airplane motors and break down faster. Engine problems have caused many of the V-22?s worst accidents and also account for much of the ballooning operational cost.

The Marines have tried different approaches to driving down the V-22?s maintenance bill. At one time the Corps even considered replacing the current engines with entirely new models. So far, nothing has worked. Four years after being declared combat-ready, the V-22 has readiness rate of just 69 percent, compared to 85 percent for a Blackhawk.

The Osprey’s growing pricetag could threaten other Marine programs. Despite their reputation for doing more with less, the Marines actually have the most ambitious aviation modernization plan of any of the military branches, according to Richard Aboulafia, an analyst at the Teal Group in Virginia.

The Marines want to buy F-35B stealth jump jets, modernized AH-1Z and UH-1Y light helicopters and the new heavyweight CH-53K chopper in addition to the V-22 — and all at the same time. Budgets are so tight that a cost increase with any of these new aircraft forces the Marines to cut back on others. Already, the Marines are considering eliminating H-1s to pay for F-35s. What would they sacrifice to afford more Ospreys?

Photo: Navy