March 23, 2009
Su-35 prototypes bort '901' and '902' accumulated 100 test flights in total, finalized flight control system tests.
The third prototype is a static airframe for ground testing only.
April 26, 2009
The fourth prototype (third flying) destroyed in high speed taxi run incident shortly before the scheduled first flight. Eugene Frolov safely ejected. Aircraft destroyed by fire, after the aircraft ran off the end of the Runway at Komsomolsk-na-Amur (Dzemgi) and hit an obstacle.
Sukhoi announced that because of the good progress with the first two prototypes, the program won't be affected by the loss.
(remember: Yakovlev claimed the Yak-130 program would not be delayed because of its prototype loss some years ago, while arguably it did have an impact)