 On 26 April 2009 , the fourth Su @-@ 35 prototype was destroyed at <unk> 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 . 
