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Thursday, May 21, 2015

V-22 Highs and Lows

R&W Staff

The last week was one of highs and lows for the Bell-Boeing V-22 tiltrotor.

On May 16, U.S. special-operations troops were flown into southeastern Syria to kill a senior Islamic State in Syria (ISIS) leader there. Reportedly, CV-22s from the Air Force Special Operations joined Sikorsky Aircraft MH-60 Black Hawks in carrying the commandos on that mission.

Described as the first successful raid by American ground troops since the military campaign against ISIS began last year, the mission garnered much intelligence material while incurring no American casualties (despite hand-to-hand combat and aircraft struck by ground fire).

Elsewhere, MV-22s from the U.S. Marine Corps’ Marine Medium Tiltrotor Squadron 262 (the “Flying Tigers”) have been carrying critical supplies to survivors of April 25’s magnitude 7.8 earthquake in Nepal.

But a fatal May 17 MV-22 accident in Hawaii prompted politicians and the public to again ask, “Is the V-22 safe?” (Japan's Kyodo news service reported that the governor of Okinawa in southern Japan, where 24 U.S. V-22s are stationed, demanded that Osprey flights be suspended until the crash’s cause is determined.)

The Osprey from Marine Medium Tiltrotor Squadron 161 Reinforced (the "Greyhawks") crashed after suffering what the USMC described as a hard landing during routine training. The aircraft was one of several that had departed the USS Essex about 100 miles off Oahu, transporting 21 Marines and a U.S. Navy corpsman to Bellows Air Force Station near Waimanalo, Oahu.

As the aircraft transitioned from airplane to helicopter mode at about 11:40 local time, it crashed. One Marine was killed and at least one other person onboard was critically injured.

Like helicopters, the V-22 is susceptible to vortex ring state, a condition in descent in which vortices normally shed clear of the rotor blades become trapped around the rotor. This essentially prevents the production of rotor thrust and results in a sudden descent.

Because of the V-22’s configuration, vortex ring state also can produce a sudden hard roll if only one of its lateral rotors is affected. This combination is considered a contributing cause of the April 8, 2000 crash at Marana, Ariz. that killed 19 Marines. That crash was one of two that led to a 17-month grounding of the V-22.

The cause of the May 17 crash is under investigation.

Related: Military News

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