Incident Overview
A helicopter engaged in a sling load operation on an offshore platform experienced an engine failure. The aircraft was in the process of picking up a sling load when the failure occurred.
Sequence of Events
Following the engine failure, the pilot initiated an autorotation. During the descent, the left skid and float collided with a handrail on the rig, causing them to separate from the aircraft. The helicopter subsequently impacted the water in a nose‑low attitude and rolled over. The rollover was attributed to the missing float, which had separated during the collision.
Investigation Findings
Examination of the failed engine revealed that the engine failure was caused by a fatigue failure of the 6th stage compressor wheel. The fatigue crack originated at a casting inclusion that had not been detected during the manufacturing process. No other contributing factors were identified in the source.