Incident Overview
While cruising at an altitude of 550 feet above the Gulf of Mexico, the pilot observed high turbine outlet temperature (TOT) indications. Shortly thereafter, the N1 RPM dropped and the engine failed. The pilot initiated an autorotation, which ended in a hard landing on the water where waves were approximately 5 feet high.
Emergency Float Separation and Rollover
During the landing, one of the helicopter's emergency floats separated from the airframe. The helicopter subsequently rolled onto its side but remained afloat, preventing a complete submersion.
Engine Teardown Findings
A teardown inspection of the engine was conducted to determine the cause of the failure. The examination revealed that a second-stage compressor wheel blade, part number 6890502, had failed. This failure resulted in severe damage to the second and fourth stage areas of the engine, consistent with a catastrophic internal failure.
Conclusion
The investigation determined that the engine failure was due to a fractured second-stage compressor blade, which led to extensive damage to multiple compressor stages. No other contributing factors were identified in the source material.