All V-22s Grounded, Probe Finds Materiel Failure Possible In USAF Crash

A U.S. Air Force CV-22 lands at Goodfellow AFB, Texas, in 2021.

Credit: U.S. Air Force

The entire Bell Boeing V-22 fleet has been grounded after a preliminary U.S. Air Force investigation into the Nov. 29 crash near Japan found that a “potential materiel failure” could have caused the mishap.

Air Force Special Operations Command (AFSOC) boss Lt. Gen. Tony Bauernfeind ordered the operational stand down of the command’s fleet on Dec. 6, shortly after Naval Air Systems Command (NAVAIR) instituted a grounding bulletin for all its V-22 variants. It is the second time this year that V-22s from all U.S. military services have been grounded. The Japan Maritime Self Defense Force had also grounded its V-22s following the Nov. 29 crash.

The Air Force CV-22 crashed into waters near Yakushima, Japan, during a training mission, killing all eight on board. Eyewitnesses reported seeing an engine on fire before the aircraft crashed into the sea. The remains of all eight have been recovered, the Air Force said Dec. 6.

AFSOC did not expand on the potential materiel failure that could have caused the crash, saying that causal factors will be determined as part of the accident investigation.

“The stand down will provide time and space for a thorough investigation to determine causal factors and recommendations to ensure the Air Force CV-22 fleet to return to flight operations,” the command says.

In a statement, NAVAIR added that “the mishap remains under investigation, we are implementing additional risk mitigation controls to ensure the safety of our service members.”

The Nov. 29 crash was the fourth V-22 hull loss within the past two years, and the first involving a U.S. Air Force CV-22. An MV-22 crash in Australia killed three people in August 2023. An MV-22 crash in California killed five in June 2022, and an MV-22 crash in Norway killed four in March 2022.

An investigation found the June 2022 crash was caused by a long-known problem with the Osprey’s gearbox, a hard-clutch engagement. The root cause of the issue has not yet been determined. In February 2023, the Joint Program Office announced an effort to attempt to mitigate the issue by replacing the gearbox’s input quill assembly (IQA) every 800 flight hours.

Bauernfeind told Aerospace DAILY in September that the replacements will be indefinite until the issue is further understood, with each replacement taking at first about six days. AFSOC said in a statement it does not yet know the status of the IQA replacement on the V-22 that crashed.

The order is the second V-22 grounding within the past three months after a Marine Corps-wide aviation stand down following the Australia crash. The Air Force first grounded its fleet in August 2022 after an Osprey experienced a hard landing, though the Marine Corps and Navy did not follow suit. The entire fleet was grounded as IQA replacements started beginning in February and aircraft returned to flight as replacements were completed.

Brian Everstine

Brian Everstine is the Pentagon Editor for Aviation Week, based in Washington, D.C. Before joining Aviation Week in August 2021, he covered the Pentagon for Air Force Magazine. Brian began covering defense aviation in 2011 as a reporter for Military Times.


Navy might now view the old COD in a better light.
Material is a substance out of which something is made, while materiel is equipment and supplies used by an organization.
The COD change may be delayed, but it’s going to happen. There are too many logistical advantages to operating the CMV-22 to ignore.
Moving beyond my previous flippant comment, tiltrotor difficulties serve to emphatically underline the urgent need for a completely new VTOL lift system architecture. A combination of available and emerging technologies is just now making that possible. That lift system would yield significant increases in speed and range for any given vertically lifted payload, at any scale. (I think that, initially, 400 knots is too far a reach.) I believe I understand what the essential configuration must be: I just don't see it represented in the industry development space.
If I recall, the absolute speed limit with a helicopter is 250 mph due to the fact (I've been told) that the trailing main blades in forward flight begin to suffer a stalling effect at high speed. Hence one will never see super high speed helis.
That's the deal with the V-22. Can fly as a heli for landing/takeoff if desired and then rotate the engines to horizontal for a high speed dash as a conventional plane. If desired, the engines can be canted from vertical for a rolling short field takeoff from a runway. I believe they use that when carrying a heavy load with fuel. Fantastic new technology in my eyes and unfortunately there can be bugs even this late into the game. I have no doubt the engineers will sort it out as those capabilities are too important to lose.