NTSB Identification: MIA96LA028.
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Accident occurred Wednesday, November 15, 1995 in JASPER, FL
Probable Cause Approval Date: 02/08/1996
Aircraft: BELL 47-D1, registration: N4702S
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 STATED HE WAS MAKING AN APPROACH FOR LANDING AT A FIELD SITE WHEN THE HELICOPTER EXPERIENCED A PARTIAL LOSS OF ENGINE POWER. HE LOWERED THE COLLECTIVE AND ROLLED THE THROTTLE TO THE FULL ON POSITION. THE HELICOPTER COLLIDED WITH POWER LINES AND THE GROUND. REVIEW OF THE AIRCRAFT LOG BOOKS REVEALED THAT THE LAST ANNUAL INSPECTION WAS COMPLETED 3 MONTHS BEFORE THE ACCIDENT. THE CARBURETOR WAS NOT APPROVED FOR USE BY THE FRANKLIN ENGINE COMPANY. EXAMINATION OF THE CARBURETOR HEAT CONTROL VALVE REVEALED AN INCORRECT SPRING INSTALLED, AND THE CARBURETOR HEAT COULD NOT BE ACTIVATED FROM THE COCKPIT. THE CARBURETOR ICING PROBABILITY CHART SHOWS THE POSSIBILITY OF CARBURETOR ICING CONDITIONS BASED ON THE WEATHER AT THE TIME OF THE ACCIDENT. PRIOR TO THE APPROACH, THE PILOT HAD COMPLETED THE BEFORE-LANDING CHECK WITHOUT THE AID OF A CHECKLIST, AND THE CARBURETOR HEAT WAS NOT TURNED ON.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

IMPROPER MAINTENANCE AND INSPECTION OF THE CARBURETOR SYSTEM BY MAINTENANCE PERSONNEL DURING THE LAST ANNUAL INSPECTION WHICH RESULTED IN A PARTIAL LOSS OF ENGINE POWER DUE TO CARBURETOR ICE. CONTRIBUTING TO THE ACCIDENT WERE: THE PILOT'S FAILURE TO PERFORM AN ADEQUATE PREFLIGHT AND ENGINE RUN-UP, AND THE CARBUETOR ICING CONDITIONS.

Full narrative available

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