An air crash due to failure of compressor rotor

A fighter aircraft crashed in an accident. Initial investigations pointed out that the accident was due to the failure of compressor rotor. The engine had a nine-stage axial flow compressor in which the nine disks were joined together through riveting. After accident a number of blades and broken pieces of outer ring of the 9th stage compressor disc were found scattered on the runway and near the crashed aircraft. On the removal of the engine from the aircraft, the mid casing was found ruptured. Initial investigation concluded that the failure of 9th stage disc of compressor rotor caused the aircraft crash.Failure analysis of 9th stage disk showed that the disk failed due to fatigue which started from one of the six holes present on the disk. The origin of fatigue crack was machining marks, which were present on the surface of the disk. The crack traveled ∼30 mm in length before final catastrophic failure. Cracks were also observed around other holes on the disk; they were starting from machining marks. The failure of ring and blades were subsequent.