U.S.A.F. Grounds Osprey Tiltrotor Aircraft after Clutch Problem: Report

The U.S. Air Force Special Operations Command (AFSOC) has grounded 52 CV-22 Osprey aircraft after it found problems with its clutch.

AFSOC public affairs director Lt. Col. Becky Heyse confirmed in an email to Defense News that the command’s Osprey fleet were grounded to ensure airmen’s safety on August 16 due to recent “hard clutch engagement” incidents. Two such problems have happened in the last six weeks, and there were previously two others that occurred since 2017.

As per the report, no one was injured as a result of the four clutch problems.

“We absolutely owe the air crew information about why this is happening and how we’re going to mitigate it,” Heyse said. “Because we don’t have that now, Gen. Slife didn’t feel comfortable flying them.”

The stand-down and clutch problem was first reported by Breaking Defense.

Hard clutch engagement occurs when the clutch connecting the propeller’s rotor gear box to its engine slips. When this happens, Ospreys are designed to transfer the power load from that engine to the other engine immediately, which would allow it to keep operating if an engine failed.

In these incidents, the clutch on the original gear box has engaged and the power load transferred back, within a span of milliseconds. The large transfer of torque causes the Osprey to lurch, and the air crews land immediately. These problems in the past have led to the replacement of Ospreys’ gear boxes and engines, which qualified them as Class A mishaps.

Heyse said AFSOC is not sure whether it is a mechanical, design or software problem causing these hard clutch engagements, and as a result can’t put solutions in place to stop it from happening again until the command knows more. It is not yet known how long the Ospreys will be grounded.