After greater than a dozen MV-22 Osprey incidents involving what is called a tough clutch engagement, or HCE — together with one which claimed the lives of 5 Marines — army officers now say that they’ve lastly made progress in understanding the lethal subject.
“Whereas the final word root trigger has not but been verified, the HCE crew has narrowed down the scope of the investigation to a number one idea,” Neil Lobeda, a spokesman for the Osprey’s Joint Program Workplace, instructed Army.com in an e mail.
That idea, based on Lobeda, is one thing referred to as “out of section engagement.”
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The Osprey is exclusive in that it’s a tilt-rotor plane, which means it lifts off like a helicopter however flies like a standard airplane. With that design, it additionally implies that the Osprey is restricted in its capacity to recuperate from a problem, ought to one happen.
In contrast to fixed-wing plane, it isn’t capable of be geared up with ejection seats or glide to a touchdown. It additionally is not capable of make use of “autorotation” — a security maneuver helicopters use the place the engine is disengaged and the rotors spin as air strikes previous them whereas descending.
Consequently, it’s geared up with a fancy system of clutches and linkages which can be designed to deal with a state of affairs the place the plane loses energy in a single engine. That system permits the second engine to nonetheless flip each propellers and preserve the plane flying.
In a tough clutch engagement, based on an Air Power official, a slip in a single engine’s clutch, “causes the engine [system] to switch all the facility into one of many [two] engines to maintain the Osprey within the air.”
The result’s that, typically, the system appears to shred itself from the within, making a state of affairs that may result in a tough touchdown or, within the case of the Marine flight in 2022, a lethal crash .
In keeping with Lobeda, the system makes use of “sprag clutches” — a mechanism like a ball bearing, however as an alternative of spheres, there are rectangular “sprags” situated between the 2 rotating elements. That allows the free rotation in a single path and the appliance of drive when one part desires to rotate in the wrong way.
The concept is that all the sprags catch without delay, however based on Lobeda, “if a few of the sprags have interaction earlier than or after the remainder of the sprags within the clutch, the engagement is then ‘non-uniform.'”
“Non-uniform sprag operation might end in slipping and/or speedy disengagement and re-engagement,” Lobeda mentioned when requested about how an “out of section engagement” could result in a tough clutch engagement.
An official and definitive identification of the foundation explanation for the clutch points aboard the Osprey is vital as a result of the army’s present repair — changing a clutch part after a sure variety of flight hours — seems to be based mostly on an evaluation finished in 2023 on what occurred within the 16 clutch incidents recognized on the time, slightly than a full understanding of what truly causes HCEs.
Regardless of the limitation, the workplace that oversees the Osprey had proclaimed final yr that the substitute would stop 99% of future exhausting clutch engagements.
Throughout a congressional listening to final week, Vice Adm. Carl Chebi, head of Naval Air Techniques Command, mentioned there have now been a complete of 19 HCE incidents in the course of the lifetime of the Osprey program, which started within the late Eighties. The fleet turned totally operational by the mid- to late 2000s.
The sooner declare — that nearly all HCE incidents may very well be prevented by changing the clutch part — was met with skepticism from specialists and a few households of the 5 Marines killed within the June 2022 Osprey crash in California.
A few of these members of the family filed a wrongful dying lawsuit final month towards the businesses that manufacture the plane, pointing to failures with the Osprey’s interconnect drive system, the problems with the exhausting clutch engagements, and flaws within the plane’s engine-controlling laptop, Army.com reported.
Whereas officers have been fairly public with the 99% declare final yr, it has not been touted just lately, and not one of the army representatives talked about it in the course of the congressional listening to final week into the security of the plane.
Lobeda instructed Army.com that the workplace nonetheless stands by the declare, however he mentioned there’s “ongoing testing and clutch put on analytical investigations … that will or could not inform an replace to the present evaluation.”
Whereas Chebi didn’t repeat the 99% determine in the course of the congressional listening to, he talked about that “there have been no exhausting clutch occasions” since implementing the time restriction on the clutch part substitute.
In the summertime of 2022, the Air Power grounded its fleet of Ospreys due to the exhausting clutch engagements and lifted it two weeks later with out a everlasting repair. An undisclosed variety of Ospreys have been grounded once more briefly in 2023 as a consequence of clutch points because the clutch part, often called the enter quill meeting, on the plane was being changed.
Shortly following an Air Power Osprey crash off the coast of Japan in November 2023 — which killed eight airmen — all of the army providers that fly the Osprey grounded the troubled plane.
Whereas investigations into that crash are nonetheless ongoing, officers mentioned the reason for the November incident was due, seemingly, to a elements failure however added that it was a problem that had not been seen earlier than.
By March, the army lifted the grounding, and the Marine Corps and Navy shortly resumed flight operations. The Air Power is slowly resuming flight operations, telling Army.com final week that “a number of” of the plane of their fleet are again within the sky.
Army.com reported final month that the providers can’t fly the Osprey greater than half-hour from a protected touchdown area within the wake of the lethal crash as a part of a Joint Program Workplace restriction.
Chebi mentioned throughout final week’s listening to that he didn’t count on the Osprey to renew full unrestricted operations till he was assured there had been property security fixes, saying “this is not going to happen earlier than mid-2025.”
