2009. April 2010 In April 2010, a CV-22 crashed near the city of Qalat in Zabul Province, Afghanistan. Three US service members and one civilian were killed and 16 injured in the crash. Initially, it was unclear if the accident was caused by enemy fire. The loaded CV-22B was at its hovering capability limit, landing at night near Qalat (altitude approx. 5,000 feet) in brownout conditions, in turbulence due to the location in a gully. The USAF investigation ruled out brownout conditions, enemy fire, and vortex ring state as causes. The investigation found several factors that significantly contributed to the crash: these include low visibility, a poorly-executed approach, loss of situational awareness, and a high descent rate. Brig. Gen. Donald Harvel, board president of the first investigation into the crash, fingered the "unidentified contrails" during the last 17 seconds of flight as indications of engine troubles. Harvel has become a critic of the aircraft since his retirement and states that his retirement was placed on hold for two years to silence him from speaking publicly about his concerns about the aircraft's safety. The actual causes of the crash may never be known because US military aircraft destroyed the wreckage and black box recorder. Former USAF chief V-22 systems engineer Eric Braganca stated that the V-22's engines normally emit puffs of smoke and the data recorders showed that the engines were operating normally at that time. April 2012 On 11 April 2012, an MV-22 from the VMM-261 on crashed near Tan Tan and Agadir, Morocco, during a joint training exercise, named "African Lion". Two Marines were killed and two others were seriously injured, and the aircraft was lost. U.S. investigators found no mechanical flaw with the aircraft, and human error was determined to be the cause. June 2012 On 13 June 2012, a USAF CV-22 crashed at Eglin Air Force Base in Florida during training. All five aboard were injured; two were released from the hospital shortly after. The aircraft came to rest upside-down and received major damage. The cause of the crash was determined to be pilot error, with the CV-22 flying through the proprotor wash of another aircraft. The USAF restarted formation flight training in response. May 2015 One of three Osprey aircraft participating in a training exercise at Bellows Air Force Station (Waimanalo, Oahu, Hawaii) suffered from dust intake to the right engine, sustained a hard landing with