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

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.