SQUAW VALLEY, CA, USA
N214RM
BELL 214B-1
THE HELICOPTER WAS ENGAGED IN LOWERING A LARGE POLE TO THE GROUND WHEN THE ENG FAILED CATASTROPHICALLY DUE TO A TOTAL FIRST TURBINE ROTOR DISC FAILURE. THE PLT TURNED THE ACFT DOWN THE MOUNTAIN BUT WAS UNABLE TO GAIN ENOUGH SPEED TO AUTOROTATE. THE ACFT IMPACTED AT AN ANGLE AND BURNED. NO PARTS OF THE FIRST TURBINE ROTOR DISC WERE RECOVERED, THEREFORE, A FAILURE MODE COULD NOT BE DETERMINED. THE DISC HAD ACCUMULATED 2776 CYCLES AT THE TIME OF THE ACCIDENT. LYCOMING SERVICE BULLETIN NO. 5508-0002 REPORTS THE SERVICE LIFE LIMIT FOR THE DISC IS 2700 CYCLES. AN ENG TEARDOWN REVEALED NOTHING ELSE WRONG WITH THE ENG THAT COULD HAVE CONTRIBUTED TO ITS FAILURE OTHER THAN THE FIRST TURBINE ROTOR DISC DISINTEGRATION.
Source: NTSB Aviation Accident Database
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