 On 26 April 2009, the fourth Su-35 prototype was destroyed at Dzemgi Airport during a taxi run. The aircraft crashed into a barrier at the end of the runway, burned, and was written off. The pilot, Yevgeny Frolov, ejected and was taken to hospital with burns and other injuries. The aircraft was expected to be the third flying prototype, with its first flight scheduled on 24 April, which was rescheduled for 27 April. A commission was opened to investigate the crash, but several sources initially speculated that the incident had been the result of a brake failure or a faulty fuel pump.
