Ospreys Cleared to Fly Again, But Problematic Gearbox Gets More Scrutiny

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A U.S. Marine Corps MV-22B takes off from the a USS Boxer
A U.S. Marine Corps MV-22B takes off from the amphibious assault ship USS Boxer in the Pacific Ocean Nov. 22, 2024. (U.S. Marine Corps photo by Cpl. Joseph Helms)

The Navy office that oversees the military's use of the V-22 Osprey is allowing the services to resume flying the aircraft while ordering yet another key component -- one that has led to at least one deadly crash -- to undergo further scrutiny.

The office's statement, released Friday, says that every Osprey's proprotor gearbox -- a key piece of machinery that transfers power from the engines to the aircraft's rotor blades -- needs to have the number of flight hours it has worked verified and then be subject to unnamed "flight controls."

The development comes after an incident during a Nov. 20 training mission with a CV-22 Osprey at Cannon Air Force Base in New Mexico when, "out of an abundance of caution," the Navy's office "recommended an operational pause for all V-22 Osprey variants" on Dec. 6. It also comes more than a year after a gear failure in an Air Force Osprey caused a crash off the coast of Japan that killed eight airmen.

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The office, Naval Air Systems Command, or NAVAIR, said in its statement that Ospreys whose gearboxes meet or exceed a "predetermined flight-hour threshold" can resume flying in accordance with restrictions that were put out in a March 2024 interim flight clearance document.

Meanwhile, Ospreys whose gearboxes are under this new flight-hour limit will be subject to a new interim flight clearance requirement that will also contain "additional risk mitigation controls."

    In its statement, NAVAIR noted that it will not make public the new flight-hour threshold for the gearboxes, what the additional flight controls are, or how many Ospreys are impacted -- a move that continues a tradition of hiding key details and metrics about the aircraft and just how safe it is to fly amid mounting mishaps and deaths.

    The statement cited "operational security concerns" as the reason for the secrecy, while also claiming that officials remain "committed to transparency and safety regarding all V-22 operations."

    NAVAIR did not immediately respond to follow-up questions from Military.com asking for specifics about the limitations.

    The latest restrictions also eerily mirror NAVAIR's response to the issue of hard clutch engagements -- another mechanical issue that plagued the Osprey for years before it finally turned deadly, killing 5 Marine aviators in 2022.

    In February 2023, NAVAIR declared that, while it didn't have a clear understanding of what causes the problem, replacing a part of the drivetrain called an input quill assembly would reduce further issues by more than 99%.

    When NAVAIR announced that fix, it also refused to say how many flight hours it would take before that replacement is needed, how many Ospreys had been grounded, or how long those flight restrictions would last.

    Since then, NAVAIR has said it stands by the claim that the quill replacement effort eliminated 99% of hard clutch engagements, but officials haven't publicly cited the figure since 2023.

    In a congressional hearing this summer on the Osprey's safety, none of the military representatives cited the statistic, and a NAVAIR spokesman told Military.com that there was "ongoing testing and clutch wear analytical investigations ... that may or may not inform an update to the existing analysis."

    The myriad issues with the Osprey's gearboxes have come to light in the wake of the deadly crash of a CV-22, call sign Gundam 22, off the coast of Japan in November 2023 that claimed the lives of eight airmen.

    Military.com first and exclusively revealed details from an internal safety board investigation that showed the shattering of a single, poorly made high-speed planetary pinion gear inside a proprotor gearbox was to blame in the Gundam 22 crash, and it was an issue that NAVAIR was aware of for nearly a decade.

    The internal report showed that the gear failure was similar to seven other incidents and that a subcontractor, Universal Stainless, was the company that made the gear that failed in Gundam 22.

    Military.com also reported on allegations that the company had crafted substandard steel for aircraft parts stretching back to a 2001 lawsuit and that neither the aircraft manufacturers nor NAVAIR would say whether Universal Stainless was still making parts for the aircraft.

    The aircraft manufacturers are now facing two separate wrongful death lawsuits brought by the family of an airman killed in the 2023 Air Force crash and families of the Marines who were killed in the earlier 2022 Marine Corps crash.

    Related: Military Ospreys Can't Fly More Than 30 Minutes from Landing Airfield Months After Grounding Lifted

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