The US military has cleared the Bell-Boeing V-22 Osprey tiltrotor to resume flight operations, more than three months after a fatal crash off the Japanese coast killed eight American personnel.
Airworthiness authorities at the Pentagon grounded the entire Osprey fleet shortly after that incident, covering more than 400 aircraft across the navy, air force and marine corps.
Now, those same regulators say they are confident the troubled tiltrotor can be safely returned to duty, based on data collected from multiple investigations into the November crash.
“We have high confidence that we understand what component failed and how it failed,” says Colonel Brian Taylor, V-22 programme manager at the US Naval Air Systems Command (NAVAIR), which serves as the airworthiness authority for the tiltrotor.
While Taylor would not reveal the exact nature of the failure, or even which component was involved, the Sikorsky CH-53E pilot says the issue had not been observed in previous Osprey mishaps.
“This is the first time we have seen this particular component fail in this way,” Taylor reveals. “This is unprecedented.”
That is a significant claim for a platform Taylor says has logged approximately 750,000 flight hours across the combined fleets of the US Navy (USN), US Air Force (USAF), US Marine Corps (USMC) and the Japan Ground Self-Defense Force (JGSDF).
Notably, NAVAIR’s fix for the problem does not involve any physical changes to the Osprey airframe or individual components.
Citing security concerns, Taylor would not reveal the mitigation procedures NAVAIR plans to deploy. However, he confirms there will be revised maintenance guidelines and changes to some in-flight procedures.
“The mitigations that we’re putting in place really address this one particular component and how it operates inside of the aircraft,” Taylor says.
The preventative measures will add an “extra perimeter of safety”, he adds, while still allowing the component in question to perform its mechanical function. Taylor likens the changes to shortening the interval between oil changes on a personal vehicle – performing an existing maintenance procedure more frequently.
However, significant questions about the deadly crash remain unanswered – chief among them, why the problematic component failed at all.
While the mitigation measures developed by NAVAIR are intended to identify and avoid a possible mechanical failure ahead of time, investigations into the November crash still have not determined why the failure occurred.
Taylor says this is in part due to salt water corrosion of the V-22 wreckage, which was recovered in waters some 50 miles (80km) south of the Japanese island of Kyushu.
“While the exact why may not necessarily be determined, we understand generally the mechanics of what played out,” Taylor says. “That’s what the mitigations address,” he adds.
RETURN TO FLIGHT
Operators of the V-22 are expressing confidence in NAVAIR’s findings, and the decision to clear the Osprey for renewed flight operations.
“Our return to flight is founded on the absolute confidence in the analysis by NAVAIR,” says Brigadier General Richard Joyce, the top aviation officer within the USMC.
With 348 MV-22s currently in its fleet, the USMC is by far the largest tiltrotor operator in the world. Joyce notes the service’s 17 Osprey squadrons have approximately 240 V-22s available for front line service on any given day.
Despite the importance of the tiltrotor to USMC operations, Joyce says “there has been no race” to get the service’s Ospreys back in the air before the platform was deemed safe.
Although the November crash that precipitated the recent grounding involved a USAF CV-22, the USMC has endured its own challenges with Osprey safety over two decades of service.
Three marines were killed and five more injured in August 2023 when their MV-22 crashed near Darwin, Australia during a training flight. Separate MV-22 crashes in Norway and Southern California in 2022 killed nine USMC personnel.
The Aviation Safety Network, a service of the US non-profit Flight Safety Foundation, lists 57 mishaps and 62 fatalities associated with the Osprey since 1991. At least six of those incidents occurred during combat operations, with hostile activity a factor in some cases.
Previous Osprey crashes have been linked to the issue of hard clutch engagement, in which the tiltrotor’s clutch releases from the rotor system and then suddenly re-engages, according to NAVAIR. The hard engagement sends an impulse through the drive train, which can potentially damage the system.
That does not appear to be at issue in the latest incident. Although some facts from the crash are not yet known, Joyce says his service is satisfied with the safety measures now in place.
“We have the proper understanding, and NAVAIR applied the proper risk mitigation controls, allowing the marine corps to get back airborne safely,” the attack helicopter pilot notes.
Joyce’s counterparts in the navy and air force have expressed similar sentiment.
“I trust them implicitly”, USAF Lieutenant General Tony Bauernfeind says of NAVAIR and the decision to remove the Osprey grounding bulletin.
Bauernfeind oversees the Air Force Special Operations Command (AFSOC), whose CV-22 was the incident aircraft in the November mishap. He does not mince words when describing the cause of that crash.
“It was a catastrophic materiel failure,” Bauernfeind says.
The three-star general and Lockheed Martin MC-130 pilot has provided additional details into what caused the crash, citing a separate investigation being conducted by AFSOC.
“It was a single component that failed in such a way that led to catastrophic consequences,” he reveals.
Going a step farther than the navy, Bauernfeind says the USAF has a “high level of confidence” it knows why the failure occurred, but not enough to make a definitive conclusion.
That being the case, AFSOC will join the USN and USMC in resuming Osprey flight operations.
“I have confidence that we know enough now to return to fly,” Bauernfeind says.
Each service will develop their own return to flight plans, based on their particular operational needs and resources available. Leaders from all three US operators say the process will involve simulator training and re-certifying pilots after three months out of the cockpit.
The USMC, with its large fleet and deeper roll of instructor pilots, estimates it will take approximately 30 days for one of its Osprey squadrons to regain basic currency to perform normal flight operations.
By contrast, the USN says it will take significantly longer for its small fleet of CMV-22s to resume their operational mission of resupplying aircraft carriers at sea.
“We expect it will be several months or more before we reach this phase,” says Vice Admiral Daniel Cheever, commander of naval air forces.
Better known as the “air boss” within the USN, Cheever notes the lengthy flights over water associated with the carrier on-board delivery (COD) mission will require a longer recertification process for aircrew.
The USN has been using the nearly-retired Northrop Grumman C-2A Greyhound fixed-wing turboprop for the COD role during the Osprey grounding.
AFSOC’s Bauernfeind declines to provide a timeline for the air force’s return to flight plan, saying the resumption of normal operations will be “conditions based”.
The top officer at NAVAIR also travelled to Japan on 7 March to brief military aviators in that country on the findings of the crash investigation. The JGSDF operates 14 MV-22s.
ENDURING COMMITMENT
With yet another fatal incident caused by a previously unknown and little understood engineering issue, military leaders are being asked about the Osprey’s future.
Perhaps not surprisingly, those services which have most deeply committed to the troubled tiltrotor are doubling down.
“We’re not having conversations about anything that replaces V-22,” says USMC aviator Joyce.
The one-star general notes the marine corps is nearly complete with its planned acquisition of 360 MV-22s, with the type expected to continue service for decades to come.
In fact, Joyce says the USMC is now evaluating what modernisations will be needed to keep its Osprey fleet airworthy and operationally relevant. He describes the unique speed, range and flexibility of the type as having “fundamentally changed” USMC aviation.
Similarly, the USN has no plans to retreat from its embrace of the tiltrotor.
Despite its reliance on the Greyhound during the Osprey grounding, air boss Cheever says there are no plans to extend service of the fixed-wing COD aircraft – currently scheduled to retire in 2026.
“The Osprey delivers a critical capability to the navy,” Cheever says. “Its versatility allows for rapid deployment of personnel, critical cargo and supplies to-and-from the aircraft carriers, extending the navy’s reach and responsiveness in diverse operational profiles.”
At the Singapore air show in February, the navy’s top logistics officer in the Western Pacific praised the Osprey’s ability not only to resupply ships at sea, but also provide broader support to theatre-level logistics.
“The ability to take off and land vertically, not just on the carrier, but in austere locations, is a game changer,” said Rear Admiral Mark Melson.
By contrast, the USAF appears more open to moving on from the problem-plagued tiltrotor.
“I do think that it’s time for us to start talking about what is that next generation of capability that can replace what the V-22 does,” AFSOC’s Bauernfeind says.
While he says the Osprey has lived up to its promise of combining fixed-wing speeds and range with the vertical take-off and landing flexibility of a helicopter, Bauernfeind describes the V-22 as an “older platform” based on “1980s, first-generation tiltrotor technology”.
Although no replacement is readily available, potential alternatives are starting to take shape.
The US Army in 2023 selected a new-design tiltrotor – the Bell V-280 Valor – to be its future long-range assault platform. Produced by the same manufacturer, the Valor will in many ways be the successor to the Osprey.
Drawing upon lessons from the V-22, Bell has substantially redesigned the mechanics of the V-280 to make the transition between horizontal and vertical flight less complex.
Whereas the entire nacelle and engine assembly rotate between flight modes on the Osprey, only the rotors and driveshafts will move on the Valor – simplifying maintenance and flight operations.
Separate from the army’s development work on the V-280, US Special Operations Command and the secretive Defense Advanced Research Projects Agency are in the early stages of developing an even more radical alternative to existing tiltrotor technology.
Known as Speed and Runway Independent Technologies, or Sprint, the effort seeks to deliver a prototype aircraft that can offer vertical take-off and landing and the ability to cruise at speeds equivalent to a fixed-wing jet.
Bell has already proposed a concept it calls High-Speed Vertical Take-off and Landing for the programme, which would add a third, jet-powered flight mode to the existing tiltrotor framework.
The company has already conducted sled testing on a novel propulsion system at a high-speed test track at Holloman AFB, New Mexico.
Boeing subsidiary Aurora Flight Sciences plans to compete a blended-wing-body design that incorporates fan-in-wing rotors to provide vertical lift – what Aurora calls a “high lift, low drag” design with embedded engines and moderate sweep.
Northrop Grumman and Piasecki Aircraft are also competitors in the Sprint programme, but have not publicly released details of their designs.
Whatever the latest development programmes deliver, it appears likely the Osprey will remain a vertical-lift fixture within the US military for many years to come.
“There is no taking our eye off of V-22 and the years of service life it has in front of us,” says Joyce.
