AFSOC commander cautiously optimistic on V-22 clutch problem, though root cause elusive


CV-22 Osprey Aircrew members from the 8th Special Operations Squadron “Black Birds” perform an engine running change of crews Jan. 26, during a local training mission at Hurlburt Field, Fla. The CV-22 Ospreys primary mission of the 8th SOS is insertion, extraction, and re-supply of unconventional warfare forces and equipment into hostile or enemy-controlled territory using airland or airdrop procedures.

AFA 2022 — After temporarily grounding the CV-22 inventory last month, the head of Air Force Special Operations Command believes that the V-22 enterprise is finally on a path to fix a potentially dangerous safety issue that’s plagued operations for years.

“We’ve got a pretty good roadmap for industry on the tests we need to perform and the data that we need to collect” to isolate the root cause, as the aircraft cautiously take back to the skies, AFSOC commander Lt. Gen. Jim Slife told reporters during a Tuesday roundtable.

There have been 15 “hard clutch engagements” across the V-22 fleet — which includes the Marine Corps MV-22 and Navy’s CMV-22 — since 2010, including four that have occurred with AFSOC CV-22s.

The issue occurs when a sprag clutch — the component in a propeller rotor gearbox that allows the engine to drive the rotor — slips, driving all of the torque from one engine to the other, before re-engaging and sending that torque back to the initial engine. That massive shift in load happens “in fractions of a second,” Slife said.

Slife said he grew concerned about the issue when the second AFSOC CV-22-related incident happened in 2020, calling it “a pretty significant feat of airmanship to get this airplane safely on the ground.” Since then, Slife said he became “dissatisfied” with the progress the V-22 Joint Program Office had made to resolve the problem that other V-22s had suffered years before.

Those feelings came to a head after two more CV-22 crews experienced hard clutch engagements within a matter of six weeks this summer, prompting Slife to stand down flight operations for all 52 CV-22s on Aug. 17.

“I was asking myself, what would I say to myself in the aftermath of fatal mishap if we discovered that the reason for this was this clutch issue,” he said. “Would I look back and say that I did everything that I could do today? And I couldn’t answer that in the affirmative.”

AFSOC cleared the CV-22 for flight again on Sept. 2 after it put in place some risk mitigation techniques, even though a root cause for the problem still has not been found.

So what changed? Slife said the V-22 enterprise placed a renewed focus on the issue, with the program office finding “common threads” among incidents. Stakeholders — including. Gen. Michael Cederholm , the Marine Corps’ deputy commandant for aviation, and Vice Adm. Kenneth Whitesell, the chief of naval air forces — also came up with a detailed plan to resolve the problem.

The near-term mitigations focus on procedural changes to how the V-22 is flown, specifically “try[ing] to avoid the environments in which we have experienced the vast majority of these clutch slipping events,” Slife said. Breaking Defense previously reported that crews will be trained in simulators on what to do if a hard clutch engagement occurs. Pilots will also be instructed not to push the throttle to full power on takeoff, but rather bring the power to full more slowly.

In the mid-term, AFSOC plans to instate a new requirement to change the sprag clutch after a certain number of flight hours. Right now, the program office is still collecting data on the gearboxes to see exactly when those clutches should be replaced, Slife said, but generally the problem has occurred with gearboxes at the middle of their originally proposed service life.

Replacing the sprag clutch so soon could trigger an appetite for suppliers to increase production of that component, he said. “The supply system is going to take a while to react to that [new requirement], because we don’t replace all that many of them right now, and I’m going drive a demand signal to replace more of these things.”

In the long-term, the V-22 enterprise hopes narrow down a root cause for the problem so that a technical fix can be put into place, finally solving the issue once and for all.

The V-22 has existing tools that record data during a flight, but because a hard clutch engagement happens in “nanoseconds,” the problem looks like a momentary data spike with few of the granular details that would give engineers insight into what is going wrong. “We need to increase the sampling rate of our of our data collecting device on the aircraft and that kind of thing,” Slife said.

The Bell-Boeing V-22 has been controversial over its lifespan due to its spotty safety record. Earlier this year, a March 2022 MV-22 crash in Norway resulted in the deaths of four Marines, while a June 2022 crash in California killed five. (A Marine Corps investigation found that the March crash was due to pilot error, according to the investigation report. A Marine official said at the time of the June crash that its cause was under investigation.)

No injuries or deaths have been caused by the hard clutch engagement problem, and the Navy and Marine Corps opted to keep flying their own V-22s after news of the CV-22 grounding was reported by Breaking Defense.

“The hard clutch issue has been known to the Marine Corps since 2010, and as such, we have trained our pilots to react with the appropriate emergency control measures should the issue arise during flight,” the Marine Corps said then. “We also remain engaged with the joint program office, NAVAIR engineering, and our industry partners to resolve the issue at the root cause.”

Slife said there was “no friction” between the services due to the decision, and that the Marine Corps and Navy operate the V-22 in different environments and thus have different tolerance for certain kinds of risk.

“AFSOC does a lot more low visibility, landings with dust outs …. where we’re shooting an approach all the way to the ground without visual reference outside of the aircraft because of the dust clouds or whatever,” he said. “Our airplanes are heavier. …  Our aircraft procedures are a little bit different than the Marines’ are, so I think that’s probably the driving factor behind it.”

Leave a Reply

Your email address will not be published.