In case you've been in a vacuum for the past two decades, the V-22 is a tiltrotor aircraft. It takes of and lands verticaly like a helicopter, but flies like a conventional airplane. The Marines are currently using the Osprey operationally, the Air Force is just starting to. The Osprey has had a difficult road to production, with inumerable technical issues, high profile crashes during development, and the subject of a tug of war in Congress and the Pentagon.
The Marines use the V-22 as a troop transport. It is a replacement for the Vietnam era H-46 helicopter. They have around 60 of them in service so far.
The Air Force uses the V-22 as a Special Operations aircraft. They have only a few of them so far, and seem to be in the mode of figuring out how to use them.
The Marines have completed two combat deployments of the Osprey in Iraq. There have been no serious incidents. Many lessons about operating the Osprey, tactics needed in that environment, and maintenance considerations have been learned - which was the primary purpose of the deployments. Some goals of the deployments were not met, primarily due to the reluctance of command staff to risk the aircraft in certain situations. The loss of an operational Osprey would be a serious blow to the program, and certain career death for the squadron commander. The Marines, justifiably so, are being very careful with their transport of the future.
To date, the Air Force has not (at least to public knowledge) deployed any of theirs outside of the US.
The GAO's primary complaint seems to be that the aircraft had not been proven to be able to perform some of its intended missions. So far, those missions have not been operationally attempted. The operational test for those missions will be Afghanistan, and the aircraft has not been deployed to that theater yet. A valid point by the GAO, but it should result in an "I" for incomplete - not "F" for failure. Just because some bozo in Congress chose this moment to have the GAO testify about it, does not mean that the operational/test/deployment schedule for the aircraft revolves around the date of that testimony.
As an aviation fan, I do have concerns about this aircraft. It is wonderful technology, and a marvel to watch. It leaks hydraulic fluid like a sieve out of the engine nacelles. A crew chief told me that they don't worry about it unless the puddle on the ground reaches a certain diameter. Standard equipment, at least for the Air Force versions, is two push brooms - when it lands off pavement the rotor blast fills the cargo compartment with whatever is on the ground, including dirt, rocks, grass - whatever. The intricate mechanisms for nacelle rotation and (especially) power routing in the event of an engine failure are complex. How hard it will be to maintain them in field operations would be a concern to me, as would their vulnerability to enemy fire.
The development and test period for this aircraft have been very long, due to it's complexity and the huge changes in tactics and doctrine necessary to employ it.
It is too early to determine if it will be a success. Likewise, it is far too early to call it a failure.
Update - “It’s time to put the Osprey out of its misery, and time to put the taxpayers out of their miseries.” Rep. Edolphus Towns, D-N.Y.
The Democrat chariman of the committee said this Friday, which is no surprise - the conclusion was made before the hearing was ever convened.
Photo above is an Air Force CV-22B of the 71SOS, 58SOW, photographed last summer by yours truly