NTSB Identification: NYC95LA137.
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Accident occurred Saturday, July 01, 1995 in MALONE, NY
Probable Cause Approval Date: 11/25/1996
Aircraft: FIELD VARI-EZE, registration: CGMEZ
Injuries: 1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
THE PILOT APPLIED POWER AT THE COMPLETION OF A LOW PASS OVER A RUNWAY AND NOTICED A VIBRATION 1 TO 2 SECONDS LATER. THIS WAS FOLLOWED BY A LOSS OF PROPELLER THRUST AND HIGH ENGINE RPM. THE PILOT SECURED THE ENGINE, AND DUE TO THE LOCATION OF PERSONNEL AND TREES, INITIATED A TURN BACK TO THE RUNWAY. AT THE COMPLETION OF THE TURN, HIS APPROACH TO THE RUNWAY WAS OBSTRUCTED BY ANOTHER AIRPLANE, AND THE PILOT LANDED IN A ROUGH FIELD ADJACENT TO THE RUNWAY. DURING THE LANDING ROLL, THE MAIN LANDING GEAR AND LEFT WING SEPARATED. INVESTIGATION REVEALED THAT THE AIRPLANE WAS EQUIPPED WITH A SUBARU ENGINE AND A ONE-OF-A-KIND, THREE-BEARING, PROPELLER SPEED REDUCTION UNIT (PSRU). THE THREE-BEARING PSRU HAD REPLACED A PRODUCTION TWO-BEARING PSRU, WHICH HAD ACCUMULATED 125 HOURS SUCCESSFULLY. EXAMINATION OF THE PSRU REVEALED THAT THE PROPELLER SHAFT FAILED NEAR THE CENTER BEARING. THIS WAS DUE TO THERMAL EXPANSION OF A MOUNTING PLATE, WHICH RESULTED IN A BENDING OF THE SHAFT AT THE CENTER BEARING.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: failure of the propeller speed reduction unit due to an inadequate design change by the manufacturer, which resulted in a complete loss of thrust. A factor was the rough terrain. Full narrative available
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