Soyuz 33 was an April, 1979, Soviet crewed space flight to the Salyut 6 space station. It was the ninth mission to the orbiting facility, but an engine failure forced the mission to be aborted, and the crew had to return to Earth before docking with the station. It was the first failure of a Soyuz engine during orbital operations.
Commander Soviet Union - Nikolai Rukavishnikov
Research cosmonaut Bulgaria - Georgi Ivanov
Commander Soviet Union - Yuri Romanenko
Research cosmonaut Bulgaria - Aleksandar Aleksandrov