CV-22B Accident Near Qalat, Afghanistan (06-0031)

Accident Overview and Casualties On 9 April 2010, a CV-22B with tail number 06-0031 impacted the ground near Qalat, Afghanistan, at 0039 local time. The aircraft was assigned to the 8th Special Operations Squadron, 1st Special Operations Wing, at Hurlburt Field, Florida. The mishap pilot, mishap flight engineer, and two passengers died. The copilot, tail scanner, and 14 other passengers sustained injuries of varying degrees. ## Investigation and Contributing Factors The Accident Investigation Board initially could not determine a cause by clear and convincing evidence. However, the Board President determined by a preponderance of the evidence that ten factors substantially contributed to the mishap, with engine power loss identified as one of those factors. ## Reopened Investigation and Technical Analysis On 15 November 2010, the Air Force Chief of Staff directed the investigation to be reopened to review additional documents, including a structural evaluation and independent assessment from Naval Air Systems Command. The Board President also reviewed a newly available video analysis that measured the aircraft's speed at initial impact at 80 knots ground speed, rather than the approximately 75 knots in the original report. ## Structural and Performance Findings The structural evaluation confirmed that the post-impact breakup was a reasonable response to the impact sequence. The lead structural engineer estimated that the aircraft decelerated between 10% and 50% of its initial impact speed after the nose plowed into the ground and struck a two-foot deep drainage ditch. The 'broomstraw' failure of the proprotor blades and the tearing away of both nacelles supported the assertion that the rotors were turning upon impact, indicating at least one engine was operational. ## Go-Around Performance Assessment The Aeromechanics Safety Investigation Support Team conducted simulation analysis using the Manned Flight Simulator models. The simulations demonstrated that adequate go-around performance existed for both all engines operating and one engine inoperative conditions until just seconds prior to impact.