What happened
On 9 April 2010, a CV-22B, TIN 06-0031, assigned to the 8th Special Operations Squadron, 1st Special Operations Wing, crashed near Qalat, Afghanistan. During the landing sequence, the aircraft impacted the ground at approximately 0039L. The accident resulted in four fatalities, including the pilot, the flight engineer, and two passengers. Additionally, the copilot, the tail scanner, and 14 other passengers sustained various injuries.
The investigation
The initial Accident Investigation Board (AIB) report was submitted on 25 August 2010, but the investigation was later reopened by the Air Force Chief of Staff in November 2010 to evaluate new evidence. This included a structural evaluation from Naval Air Systems Command (NAVAIR) and advanced imagery analysis using National Technical Means (NTM) resources.
Technical analysts examined the aircraft's deceleration after hitting a natural drainage ditch and analyzed proprotor blade strikes on the ground. While an independent assessment by the Aeromechanics Safety Investigation Support Team (ASIST) initially suggested the crash was due to a loss of situational awareness during a low visibility approach, the Board President reviewed new data regarding the aircraft's speed and proprotor revolutions per minute (Nr). The updated analysis determined the aircraft's ground speed at initial impact was 80 knots.
Findings
While the Board could not determine a cause with clear and convincing evidence, it identified ten substantial contributing factors. Based on the weight of the evidence, the Board concluded that engine power loss was one of these significant factors. This conclusion was supported by the observation that proprotor RPM was lower than normal at the time of impact, as evidenced by the spacing of blade strikes and the calculated ground speed. Furthermore, testimony from a passenger described an intense cockpit conversation regarding something going catastrophically wrong with the aircraft shortly before the impact.