Questions asked about V-22 Osprey, the tiltrotor aircraft that has claimed 62 lives
The Bell Boeing V-22 Osprey is unique, being a tiltrotor military transport and cargo aircraft that offers both vertical and short take-off and landing capabilities.
The Osprey is operated by the United States and Japan, who appreciate the fact that it blends the functionality of a regular helicopter with the long-range and high-speed capability of a fixed-wing aircraft.
The V-22 first flew in 1989 and entered service in 2007, and is known to have been involved in 63 "occurrences" – with 62 people being killed.
According to the US Aviation Safety Network, an occurrence can be anything from a warning light coming on to a hard landing or fatal crash.
Both the US and Japan temporarily ground either individual aircraft or sometimes their entire Osprey fleet in the wake of an occurrence.
Pilot error may be to blame – as was the case in October 2024 with a Japanese Ground Self-Defence force Osprey.
This began rolling left and right after an aborted take-off, resulting in the aircraft's left engine nacelle hitting the ground, although nobody was injured.
Mechanical failure
But questions continue to be raised about whether or not the aircraft is inherently safe – and, if not, what could be used to replace it.
Aviation expert Bill Sweetman told BFBS Forces News how one of the recent occurrences was linked to a mechanical failure in part of the drive system.
He said: "This comes after an accident last year where a US Air Force V-22 crashed off the coast of Japan and the occupants unfortunately were lost.
"And that was again, it seems, to have been due to mechanical failures, the breakage of some of the gear wheels in the transmission of the top rotor."
In United States service, the Osprey is flown mainly by the US Marine Corps, but is also used by the US Navy to deliver cargo to ships at sea and by the US Air Force for special operations.
No alternatives
Despite its seemingly poor accident record, Mr Sweetman said there were no obvious alternatives that could be used to replace the Osprey, should it be pulled from active service.
"It's not possible, for example, simply to replace it by the Chinook, because the Chinook is not designed to be carried on ships," he explained.
"It stands too high off the ground to fit inside the hangars of the amphibious ships that the Marines use.
"So there's no real substitute for it for special operations. The speed and range is very advantageous.
"Quite simply, you can get in and out over a longer distance under the cover of night, which is what they really care about."
He suggested one of the Osprey's main weaknesses was the small size of the rotor blades and the necessary power that had to be put through the rotors to compensate.
"It's a pretty heavy helicopter," he said. "It is quite large and very powerful. Its rotors are relatively small.
"When you have smaller rotors, you need to put more power in them.
"So you've got very, very finely loaded transmissions between the rotor, that spins at perhaps a few hundred rpm, and the engine, which is going 15,000 rpm, and problems in that area are almost to be expected."
Huge amount of power
Because the rotors are spinning so fast, the Osprey creates far more downwash than a conventional helicopter's larger blades that spin more slowly.
"The other problem is, again because of the relatively small rotor, very rapid downwash below the aircraft. Standing underneath this thing is like being in a tornado," he said.
"If you watch Marines doing a fast rope operation out of this aircraft, the first guy down has to pretty much lay down on the rope to secure it because the wind is whipping it around.
"And there are videos where the second guy down jumps on top of the first guy to hold the rope down.
"If there's any kind of loose dirt, loose soil or loose vegetation underneath the aircraft, you get a tremendous dust cloud coming up – and some of that dust is going to go into the engine inlets."
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