Summary
- Gear box failure created instant asymmetric lift causing it to roll over
- Additional blame on causal decision-making and inadequate risk management
- Investigation aims to prevent similar accidents in the future.
The Air Force Special Operations Command as released the results of an investigation into the cause of the fatal CV-22B Osprey crash in November 2023. The incident occurred during joint military exercises with Japan (which is also the only country outside of the United States to operate the Osprey). The cause of the crash has been determined to be the failure of a gear box.
Gear box failure cause instant asymmetric lift
The report states that the crash was caused by a “catastrophic failure of the left-hand prop rotor gear box that created a rapidly cascading failure of the aircraft’s drive system.” This created an “instantaneous asymmetric lift condition” that proved unrecoverable. The Osprey rolled twice and then crashed into the water.
Some blame was also attributed to causal decision-making, inadequate risk management, and ineffective crew resource management. The pilots continued to fly instead of heeding multiple warnings to land. The specific component that failed was a toothed piece called a pinion gear (a critical part of the proprotor gearbox). It is still unknown why the part failed.
According to the Air Force, the investigation examined multiple sources “including interviews, maintenance logs, flight recorder data, briefing materials, and inspection of aircraft wreckage.” They then used the information gathered to create a detailed sequence of events surrounding the CV-22 crash. The stated aim of the investigation is to identify the cause and contributing factors that led up to the mishap.
Photo: VanderWolf Images | Shutterstock
The information allows the Air Force to not only provide answers to the families of those lost in the accident but also to help prevent similar accidents from occurring again in the future.

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CV-22 Osprey
The CV-22B Osprey crash occurred on November 29, 2023. It was assigned to the 21st Special Operations Squadron of the 353rd Special Operations Wing at Yokota Air Base and flipped into the sea near Yakushima in Japan. Eight servicemembers perished in the accident, which caused the US to temporarily ground its entire fleet of Ospreys.
The CV-22 Osprey is a unique aircraft that essentially combines the attributes of a helicopter with an airplane. While it is a revolutionary new design, it has been plagued with lingering issues, and there have been four fatal crashes in the last two years. Over 400 CV-22 Ospreys have been produced and are in service with the Air Force, Navy, Marines, and the Japanese Ground Self-Defense Force.
The Osprey will not always be unique. A new family of tiltrotor aircraft is being developed for the US Army called the Bell V-280 Valor. The Army chose it in December 2022 as the winner of the Future Long-Range Assault Aircraft aimed at replacing the UH-60 Black Hawk and other helicopters. Its first deployment is expected in the early 2030s.