WASHINGTON — The Osprey, a crucial aircraft for U.S. military missions, has been authorized to resume flying after an unusual part failure caused the deaths of eight service members in a crash in Japan in November, Naval Air Systems Command announced Friday.
The crash was the second deadly accident in months and the fourth in two years. It quickly led to a rare grounding of hundreds of Ospreys across the Marine Corps, Air Force, and Navy.
Before allowing the Osprey to fly again, officials stated that they focused more on its proprotor gearbox, set new limitations on how it can be flown, and added maintenance inspections and requirements that gave them confidence it could safely return to flight.
The entire fleet was grounded on Dec. 6, just a week after eight Air Force Special Operations Command service members were killed when their CV-22B Osprey crashed off Yakushima island.
Before removing the flight restrictions, the military also briefed officials in Japan on the crash findings and new safety measures. In a statement Friday, Japan defense minister Minoru Kihara said his nation would also return its 14 Ospreys to flight status following an detailed analysis of the cause of the crash, extremely detailed information on the accident and the steps to mitigate the issue in the future.
Kihara said Japan and the United States will closely coordinate the timeline for resuming flights in Japan, to give the government time to fully explain the issue to its citizens.
However, Okinawa Gov. Denny Tamaki did not support the return to flight. Okinawa is home to Marine Corps Air Station Futenma and its 24 MV-22B Ospreys and is where the public has been most vocal in its opposition to the aircraft.
“It would be best if they stay on the ground, as we have all along requested scrapping of the Osprey deployment,” Tamaki said.
Officials who briefed reporters Wednesday ahead of the flight restrictions lifting said that they quickly grounded the entire fleet in December because it became clear that the way the Osprey part failed in that crash was something they had not seen before on the tiltrotor aircraft.
While the officials did not identify the specific component, because the Air Force’s crash investigation is still not completed, they said they now have a better — but not complete — understanding of why it failed.
“This is the first time that we’ve seen this particular component fail in this way. And so this is unprecedented,” said Marine Corps Col. Brian Taylor, V-22 joint program manager at Naval Air Systems Command, or NAVAIR, which is responsible for the V-22 program servicewide.
However, the decision by the Department of Defense to return to flight before separate congressional investigations on the Osprey program are complete drew criticism from the chair of the House Oversight Committee.
“DoD is lifting the Osprey grounding order despite not providing the Oversight Committee and the American people answers about the safety of this aircraft,” said Rep. James Comer, a Kentucky Republican. “Serious concerns remain, such as accountability measures put in place to prevent crashes, a general lack of transparency, how maintenance and operational upkeep is prioritized, and how DoD assesses risks.”
A former Osprey pilot who knows about the investigation confirmed that the part in question is a component of the proprotor gearbox, which is a critical system that consists of gearing and clutches that link the Osprey’s engine to the rotor to make it turn.
The military services have thoroughly examined the proprotor gearbox, and the new safety measures “will deal with the issues we saw from that catastrophic event,” said Lt. Gen. Tony Bauernfeind, the head of Air Force Special Operations Command, on Wednesday.
“I have confidence that we now know enough to resume flying,” he said.
The proprotor gearbox system as a whole has been a recurring problem for the Osprey. Data from the service's safety records obtained by The Associated Press show numerous occurrences among Marine Corps and Air Force Ospreys in which power surges, sudden loss of oil pressure due to leaks, engine fires or chipping, which is when the metal components inside the gearbox shed potentially dangerous metal chips, have caused damage to the proprotor gearbox during flight, sometimes requiring emergency landings.
Other parts of the proprotor gearbox, such as the sprag clutch and input quill assembly, have contributed to previous crashes, and the services have made changes, like replacing those parts more often.
The services are also examining closely the material and manufacturing process of the failed part, said Bauernfeind. NAVAIR is also conducting further tests to provide more insight into why the component failed.
“It was a single part that failed in a way that resulted in catastrophic consequences,” Bauernfeind said.
Once that testing is finished, he said, some of the operational safety controls currently in place on the Osprey may be reduced “to give us greater flexibility with the platform.”
The investigation, known as an accident investigation board, will be made public and is expected to be completed within the next two months.
The failure of the proprotor gearbox was first reported by NBC News.
Crews have not flown for more than 90 days now, which will make their return to flight more risky. The services said Wednesday they are taking a careful approach that could last from 30 days to several months to retrain their crews before their Osprey squads are back to normal flight operations.
The Osprey has been in development for four decades but only became operational in 2007. The U.S. military has flown the Osprey for about 750,000 hours and relied on its ability to fly long distances quickly like a plane and then convert to a helicopter to carry out operations in the Middle East and Africa, where some Marine Corps squadrons received an exemption from the flight ban because it was so crucial to the mission.
For future needs to counter China, the military has planned to use the Osprey in the Indo-Pacific to operate throughout islands that do not have the airfields required for traditional aircraft.
However, it has also been a controversial, first-generation military tiltrotor technology that has experienced more than 14 major accidents resulting in 59 fatalities and in some cases led to the loss of the aircraft, which costs between $70 million and $90 million depending on the variant.
None of the military branches are planning to make new V-22 production orders, which is made by a partnership between Bell Flight and Boeing. The Army has a contract with Bell Flight to purchase the Bell V-280 Valor, which is a tiltrotor similar to the Osprey but smaller and with a significant design change — the engines remain in a fixed, horizontal position. Unlike the Osprey, where the rotors and entire nacelle that houses the engine and proprotor gearbox tilt to a vertical position when it is flying in helicopter mode.
The majority of Ospreys, over 240, are operated by the Marine Corps, which has them assigned to 17 squadrons. Its aviation operations rely on the aircraft being back in flight, and the Marine Corps is committed to keeping the Osprey in its fleet until the 2050s, according to Marine Corps assistant deputy commandant for aviation Brig. Gen. Richard Joyce.
Joyce said, "We must keep a close watch on the V-22 and its many years of expected service life ahead of us."
The Air Force, which has the second largest Osprey fleet with around 50 assigned to its special operations mission, hinted on Wednesday that it might start considering other options.
The initial concepts for the Osprey go back to the 1980s, when the Iran hostage crisis revealed the need for an airframe that could move quickly and hover or land like a helicopter, said Bauernfeind.
While it has fulfilled that requirement quite effectively, it is still an older platform, he said. "I do believe it's time for us to discuss what the next generation of capability that can replace what the V-22 does."
Yamaguchi reported from Japan.
