The Air Force's CV-22 Osprey fleet will resume operations after a temporary stand-down order grounded the aircraft for two weeks due to a "high clutch engagement" issue that caused a total of four known incidents, according to a statement released by Air Force Special Operations Command.
The standdown was lifted today by AFSOC Commander Lt. Gen. James Slife, AFSOC spokeswoman Lt. Col. Rebecca Heyse wrote in the statement, though the Air Force has yet to identify the root cause of the problem.
The Osprey fleet was grounded indefinitely on Aug. 16 after officials grew increasingly concerned about the high clutch engagement issue, where the clutch would fail to connect the rotor and engine. The clutch would subsequently re-engage, causing a jolt in the aircraft. Aircrews would then be forced to land immediately.
According to Heyse, the Air Force has established “near-, mid- and long-term goals to address high clutch engagement (HCE) incidents.”
The near-term goal consists of three efforts, Heyse wrote. For the first, CV-22 crews have participated in briefings to learn how to respond to HCE incidents. The second line of effort included surveys distributed to aircrews to allow officials to evaluate their understanding of the problem and offer possible solutions.
The third effort entails one-time inspections completed by CV-22 maintainers to compare the maintenance information system with components installed on the aircraft, Heyse wrote, adding that the process will “ensure we are tracking the most accurate information in regards to drivetrain component operating times,” which are then provided to government and contractor engineering teams.
For the mid-term goal, AFSOC is evaluating the replacement of drivetrain components after a certain number of flight hours, though specific numbers were not disclosed. The long-term goal, Heyse stated, is to identify the root cause and implement a material solution.
Built by a joint Bell Textron and Boeing team, the Air Force and Marine Corps both fly variants of the Osprey.
The Marine Corps previously announced that it would not be standing down its Osprey fleet, opting instead to train aircrews how to respond if a high clutch engagement issue occurred.