The American Air Force (USAF) has concluded investigations into the accident involving one of its V-22 Osprey convertiplanes, which occurred in November last year in Japan. As determined, a catastrophic mechanical failure, combined with the pilots' inadequate response, caused the crash of the CV-22B and the death of eight soldiers.
O accident occurred at the end of November 2023, in an interoperability exercise off the coast of southern Japan. According to the report, released on 01/08 by the Air Force Special Operations Command (AFSOC), the main cause was “a catastrophic failure of the left propeller rotor gearbox that created a rapid cascading failure of the aircraft's transmission system, resulting in an instantaneous asymmetric lift condition that was unrecoverable by the accident crew.”
Eventually a large piece of gear broke, completely stopping the left rotor. The CV-22 went into a tailspin, completing two spins before impacting the sea.
This same gear failure is also attributed to other occurrences with USAF and Marine Corps V-22 aircraft. In the last two years, four fatal accidents have been recorded with the model, which is also used by the Japanese Air Force and the United States Navy.
The crash of the CV-22, combined with the model's history of problems and other incidents, led to the total shutdown of the Japanese and North American fleet. Only in March 2024 will aircraft returned to flights, even more so with restrictions.
In addition to gear failure, Air Force investigators also point to crew procedural errors among the factors, concluding that “[The pilot’s] decision-making was causal, prolonging the accident sequence and removing any consideration of an early landing at a different diversion location.”
The crew decided to continue with the mission, despite warnings from the aircraft itself about the situation in the gears. AAfter a third warning, Air Force policy says the crew needs to “land as quickly as possible.” This is a formal condition, which means that “long flights are not recommended”. Still, the landing location is up to the pilot.
The crew decided to continue with the mission before two more warnings and a more serious alert from a persistent chip in the gearbox meant the crew had to land “as quickly as possible”. They diverted to Yakushima Island in Japan, which has a small airport. For researchers, pilots “inadequately prioritized mission continuation over considerations related to the risk of prolonged flight without redundancy.”
At the same time, Lt. Gen. Michael Conley, head of AFSOC, also said the airmen did not violate any policies and acted in accordance with their training. He also states that “This is the first time this specific part has failed on a V-22 of any type in nearly 800.000 flight hours.”
