Aircrews from Marine Tilt Rotor Test and Evaluation Squadron 22 (VMX-22) recently completed shipboard landing qualifications on an amphibious assault ship, operated in Iraqi-like desert conditions in Nevada and gave orientation flights to scores of the ground Marines the Osprey is intended to carry into combat.

The preparations for the operational tests bring the Osprey program back to where it was in December 2000 when all the aircraft were grounded following a crash in North Carolina that killed four Marines. An April 2000 crash in Arizona had killed 19 Marines, including 15 from Camp Pendleton. An accident years earlier in Virginia had claimed seven lives.

Subsequent investigations by accident boards and a blue ribbon commission of aviation experts revealed a stunning history of design and manufacturing shortcuts by the construction team of Bell Helicopter and Boeing and multiple key test flights skipped by cash-short Marine officials.

But the commission found that the potential capabilities of the unusual aircraft warranted another chance.

The V-22 has been the Marines' top aviation priority for more than 20 years. The Marines hope to buy 360 MV-22s to replace the Vietnam-vintage CH-46 helicopters, which are their primary troop transports but are increasingly difficult to maintain.

What has kept the Osprey alive through decades of turmoil and tragedy is the promise of a quantum leap in performance over any current or planned helicopter.

The V-22's two jet engines and propellers can rotate from a horizontal to a vertical position, which allows it to take off and land like a helicopter but to fly twice as fast and four times as far as a chopper.

That means the Marines could launch an airborne assault from ships farther off shore and thus less vulnerable to enemy defenses. Or they could stage raids 400 miles inland, as they did with CH-53Es in Afghanistan, quicker and without refueling.

That speed and range also appeal to the Air Force Special Operations Command, which wants to buy 50 Ospreys to replace the helicopters it uses to carry commandos on their dangerous missions. In an effort to show that the Osprey can deliver its promised capabilities safely, the aircraft resumed flying in May 2002, but only in the hands of the skilled Marine and Bell-Boeing test pilots at the Naval Flight Test Center, Patuxent River, MD.

In a cautious flight test program, the test pilots and engineers have filled in the blanks in their knowledge of the Osprey's flight characteristics, including its performance in the rapid descent at slow speed conditions that caused the Arizona crash. They also have worked the bugs out of the plane's complex computer software and tested the long-overdue redesign of the V-22's leak-prone hydraulic system.

After more than 2,000 hours of accident-free flying, the test program is beginning to phase out, as VMX-22 uses the improved MV-22s and the vastly expanded performance data to train new crews in preparation for the operational evaluation.

Those carefully monitored trials will determine if the V-22 can be declared ready for operational use, including future combat. Success would allow the Osprey training squadron -VMMT-204 – to begin producing the aircrews and maintenance personnel for the first combat-ready Marine squadron.

Some future Osprey squadrons would be based in the San Diego area, either at Camp Pendleton or Miramar Marine Corps Air Station.

Despite the progress the program has made since returning to flight, doubts still linger.

Former Pentagon testing official Phillip Coyle notes that the program has yet to show that multiple aircraft can operate together on and off amphibious ships and in massed landings ashore – the way it must operate in combat.

And despite Bell-Boeing promises to improve manufacturing quality, Ospreys continue to experience parts failure, including the disintegration of an engine cooling fan that forced an emergency shutdown earlier this year.

The manufacturers also are under pressure to cut the cost per aircraft from the current price of $73 million to $58 million – which still would be twice the expected cost when then-Defense Secretary Dick Cheney tried to cancel the V-22 program as too expensive, in the late 1980s.