Marine Corps: Hard Clutch Engagement Issue Cause of Fatal MV-22B Crash

Five Marines were killed when the Osprey went down during a training exercise in Southern California in June 2022.

The MV-22 Osprey’s mission for the U.S. Marine Corps is the transportation of troops, equipment, and supplies from ships and land bases for combat assault and assault support. [Courtesy: Naval Air Systems Command]

A safety issue involving the clutch of a MV-22B was the root cause of a crash last summer that killed all five crew members on board, according to the U.S. Marine Corps.

The MV-22B went down near Glamis, California, on June 8, 2022, during a training mission. The Marines identified those on board who died as Captain Nicholas P. Losapio, Captain John J. Sax, Corporal. Nathan E. Carlson, Corporal Seth D. Rasmuson, and Lance Corporal Evan A. Strickland.

The tiltrotor aircraft was assigned to Marine Medium Tiltrotor Squadron 364, 3rd Marine Aircraft Wing, which is based in Camp Pendleton, California.

"The investigation revealed the cause of the mishap was a dual hard clutch engagement (HCE) which created a single engine and interconnect drive system (ICDS) failure; the failure resulted in a catastrophic loss of thrust on the right-hand (RH) proprotor," the Marine Corps said in a statement Friday. "The degraded drivetrain caused by the dual HCE event and subsequent single engine/ICDS failure created an unrecoverable departure from controlled flight, resulting in the tragic crash that occurred on June 8, 2022."

An investigation concluded that there was no aircraft maintenance or aircrew errors and that there was "nothing they could have done to anticipate or prevent this mishap."

Following the crash, the Marines said it took a number of actions, including installing a crash-survivable flight data recorder into all MV-22B aircraft. It also said it coordinated with the aircraft's OEM to design and field a new proprotor gearbox input quill assembly that mitigates unintentional clutch disengagements and hard clutch engagement events, as well as improve the aircraft's drivetrain and flight control system software, drivetrain component material strength, and inspection requirements.

"All USMC MV-22B commands will also present this investigation to pilots and aircrew to discuss the hazards of hard clutch engagements and [their] potential to cause a single engine/interconnect drive system failure compound emergency," the Marine Corps said.

Kimberly is managing editor of FLYING Digital.

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