JENNER, CA, USA
N1108T
HUGHES 369B
HELICOPTER WAS ON ROUTINE POLICE PATROL WHEN ENGINE FAILED AND IT AUTOROTATED TO A ROUGH LANDING ON A ROCKY BEACH. THE 1ST STAGE OF THE GAS PRODUCER SECTION OF THE TURBINE WAS FOUND FROZEN. THE TURBINE WHEEL BLADES WERE RUBBING & SEIZED TO THE 1ST STAGE TURBINE SHROUD OF THE 2ND STAGE NOZZLE ASS'Y. PIECES OF THE TURBINE BLADE'S TRAILING EDGE TIPS WERE MISSING & THERE WAS A METAL BUILDUP ON THE 2ND STAGE NOZZLE BLADE TRACK AREA. DURING DISASSEMBLY THE 1ST STAGE WHEEL HAD TO BE FORCED APART TO BREAK IT LOOSE OF THE 2ND STAGE NOZZLE. FRACTURES OF THE BLADE TIPS APPEARED TO BE CAUSED BY ELEVATED TEMPERATURE CREEP RESULTING FROM EITHER TRANSIENT OVERTEMPERATURE OR OVERSPEED CONDITIONS.
Source: NTSB Aviation Accident Database
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