The US military has grounded its entire fleet of Bell Boeing V-22 Osprey tiltrotor aircraft after a deadly crash off Japan last week. Sputnik spoke to veteran Russian combat aircraft pilot Vladimir Popov to get a better sense of the problems associated with the fledgling technology, and why the US refuses to just close the Osprey program down.
A US Air Force Special Operations CV-22B Osprey flying from Yokota Air Base in Tokyo to Marine Corps Air Station Iwakuni on Okinawa went down over the East China Sea on November 29, killing all eight airmen onboard.
The crash was at least the 40th accident involving an Osprey since the aircraft's introduction into service with the US military in 2007, with crashes killing at least 53 US service members to date.
The Osprey program is the realization of an idea going back over a century ago of a tiltrotor, also known as a convertiplane - an aircraft with the ability to take off and land vertically using helicopter-style rotors attached to its wings, and which can adjust them during flight to a something closer to an airplane turboprop engine-style configuration. This dramatically increases the convertiplane's speed characteristics relative to those of an ordinary helicopter (up to doubling them).
The United States, the Soviet Union, Nazi Germany and Britain were the first countries to begin experimenting with tiltrotor designs, with each country building prototypes from the 1930s into the early post-war period before concluding the technology was too revolutionary to be implemented effectively using equipment and materials that existed at the time.
The USSR began work on a modern-day iteration of the convertiplane in the 1970s with the Mil Mi-30 Vintoplan (lit. 'Rotorplane') project, which featured an airplane-style fuselage design and characteristics allowing it to carry up to 32 people or up to five tons of cargo. The project, envisioned as a prospective replacement for the Soviet and Russian rugged Mi-8 workhorse series fleet of helicopters, was abandoned in the mid-1990s due to lack of funding after the USSR's collapse.
The Osprey project, designed by Bell and Boeing in the 1980s and first flown in March 1989, entered mass production in 2007, and has since been introduced into service with the US Marines Corps, Air Force, Navy, and Japan's Ground Self-Defense Force. The aircraft can carry up to 24 combat troops or nine tons of cargo. The V-22 is the only convertiplane to be mass produced by any nation, with over 400 built to date.
But as often happens with complex, innovative engineering designs, the glory of having the first fully operational, mass-produced convertiplane is also a heavy burden to bear, with the United States military not only reveling in the Osprey's advantages, but suffering from its flaws, with the V-22 suffering dozens of crashes and at least 16 hull losses to date.
Last week's crash in the East China Sea was the fourth fatal incident involving a V-22 in less than two years, and follows the August 2023 Marine MV-22B crash on Melville Island, Australia during an exercise, killing three service members, the June 2022 crash of a Marine MV-22B in California, killing five troops, and an MV-22B crash in Beiarn, Norway in March 2022, which killed another four Marines.
Investigations into the latest incidents have pointed to technical problems (including a drive system failure caused by a malfunctioning gearbox in the case of the June 2022 incident in California), and pilot error in the case of the March 2022 crash in Norway.
Investigators are yet to offer details on what may have caused the November 29 CV-22B crash off Japan, although eyewitnesses have reported fire coming from one of the aircraft's engines and the Osprey reportedly flying upside down before an explosion spewed wreckage into the surrounding water.
Speaking to Sputnik about last week's Osprey crash, and asked why the US military continues to use the convertiplanes despite their crash-prone nature, Honored Military Pilot of Russia Vladimir Popov explained that it likely has to do with the resources the Pentagon has expended on the project.
"The fact is that financial resources have already been invested into the aircraft's creation and implementation," the retired Air Force Major-General with decades of service under his belt told Sputnik.
"Most likely, the engineers, designers, technologists and everyone who took part in the Osprey's development decided that its reliability can be assured, and that it can be improved in the course of operations," Popov said.
"They are likely hoping to get an effective machine, but everything remains in the stages of development and refinement. For now, of course, such an aircraft cannot really be used anywhere, since doing so means losses of personnel and money down the drain. The idea is good, but the implementation, not so much," the veteran pilot explained.
The problem with convertiplane technology at its current stage lies with the components allowing the aircraft to switch from vertical to horizontal flight mode, Popov said. "This node is 'charged' with a great deal of energy, because large loads hang on it. It may not be able to process the transition quite correctly" at times, resulting in accidents.
"Tiltrotors have been flying for a very long time, and they have a short service life. Thus, it's too early to say that it has already reached the peak of its operational maturity. What needs to be done is to clarify what went wrong in each specific case, and to approach the issue carefully and get to the bottom of it. What's also needed is to improve working with personnel, to conduct additional tests, and change the training of the pilot and crew members. The US may continue to operate Ospreys, but they need to think long and hard about how to do so without making sacrifices. Sometimes it's enough to replace only one bolt and everything will work as it should," Popov stressed.
Last week's accident may have been the result of any number of factors, from pilot error and equipment failure to errors in the mathematical calculations by the Osprey's onboard computer, Popov believes.
That said, the veteran pilot is convinced that tiltrotor technology has good prospects for the future, given its status as what is effectively a hybrid airplane/helicopter design that can accelerate to speeds of up over 550 km per hour, far above the roughly 300 km per hour achieved by modern helicopters, which have now maxed out as far as further improvements in speed characteristics go.