Here's the statement released by the International Security Assistance Force:
KABUL, Afghanistan (April 9) - A U.S. Air Force CV-22 Osprey crashed in southern Afghanistan late last night, killing three U.S. servicemembers, one civilian employee, and injuring numerous other servicemembers. The cause of the crash is unknown at this time.
The CV-22 was carrying U.S. Forces when it crashed approximately seven miles west of Qalat City, in Zabul Province. The injured were transported to a nearby base for medical treatment.The CV-22 conducts long range infiltration and resupply for U.S. Forces. It employs tilt-rotor technology that allows it to take off and land as a helicopter. While in the air the engines can roll forward, allowing the aircraft to fly faster than a standard helicopter.
The CV-22 is a modified version of the Marine MV-22.
Update: For some context on the current state of the CV-22 program, here's text from recent testimony by David Van Buren, acting assistant secretary of the air force for acquisition, who testified before Congress on March 24. (Source: CQ Congressional Testimony)
In FY11, the Air Force CV-22 Osprey program will receive the 13th CV- 22 of a 50 aircraft program of record, declaring Full Operational Capability in FY16. Air Force Special Operations Command (AFSOC) declared the CV-22's Initial Operational Capability in March 2009 and stood up the third CV-22 operating base at Cannon AFB, NM. AFSOC's CV-22s have self-deployed overseas to Africa, Central America, and most recently Iraq. They are currently enroute for another operational deployment.
The CV-22 has encountered challenges with its high operational tempo and small fleet size. This coupled with lower priority versus combat operations on spare parts has resulted in lower availability rates. The FY11 President's Budget added $126.2 million through the FYDP, for initial spares and support equipment. The Joint CV-22 Program Office along with the cooperation and support of industry partners are aggressively working to increase the reliability and availability of the CV-22 platform