A recent Air Force investigation has shed light on the cause of a tragic Osprey aircraft crash that took place off the coast of Japan last November. According to the report released on Thursday, the crash was primarily caused by cracks in a metal gear and the pilot's decision to continue flying despite multiple warnings to land. The incident resulted in the loss of eight Air Force Special Operations Command service members and prompted a prolonged grounding of the entire Osprey fleet.

The Osprey, a unique aircraft that combines the functionalities of a helicopter and an airplane, has been under scrutiny due to its safety record, with four fatal crashes occurring in the past two years. The investigation conducted by the Air Force initially attributed the crash to an unprecedented component failure. However, the recent report identified a toothed piece called a pinion gear within the proprotor gearbox as the specific cause. This gear is crucial in transmitting power from the engine to the Osprey's masts and rotor blades.

Although the Air Force is certain that the pinion gear failure was responsible for the crash, the exact reason behind the gear's failure remains unknown. The investigation also criticized the Pentagon leadership in charge of the Osprey fleet, stating that they had failed to share safety data that could have better informed the aircrews about the severity of the risks involved.

In an interview, lead investigator Lt. Gen. Michael Conley acknowledged the pilot's dedication to completing the military exercise as a contributing factor in the crash. However, he emphasized that the pilot was confident in the aircraft but not reckless in his decision-making process. The Osprey was flying along the coast of mainland Japan en route to Okinawa when the first indications of trouble began. Vibrations were recorded, but the pilot and crew were unable to access the data until after the flight.

Subsequent warnings, including chip burn notifications, were issued, indicating stress on the Osprey's gearing. The crew received six chip warnings during the flight, each presenting an opportunity to land as a precaution. However, they chose to continue the flight, disregarding the escalating warnings. As the Osprey approached an airfield at Yakushima, just half a mile away, the final chip-related warning - "chip detector fail" - was received. The investigation found that the pinion gear had broken, causing catastrophic destruction to the gearing system and leaving the crew with no chance to save themselves or the aircraft.

The crash claimed the lives of Major Eric V. Spendlove, Major Luke A. Unrath, Captain Terrell K. Brayman, Tech. Sgt. Zachary E. Lavoy, Staff Sgt. Jake M. Turnage, Senior Airman Brian K. Johnson, Staff Sgt. Jacob M. Galliher, and pilot Major Jeff Hoernemann.

As a result of the investigation's findings, changes in protocol have been implemented. Crews are now instructed to land as soon as practical upon the first chip burn warning and as soon as possible on the second. Furthermore, efforts are underway to develop a real-time vibration data system that would provide pilots with better awareness during flight.

The tragic Osprey crash in Japan has highlighted the ongoing debate surrounding the future role and safety of this unique aircraft. With investigations into its safety record and improvements being made to enhance crew awareness and response, the Osprey fleet seeks to address these concerns and ensure the safety of its service members in future operations.