# NTSB MIA96LA028: Bell 47-D1, N4702S, Jasper, FL, November 15, 1995 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 15, 1995, 11:00 local (16:00 UTC) - Place: Jasper, FL - Coordinates: 30.509397, -82.949005 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.5094&lon=-82.9490&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 8, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 37950 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA96LA028 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37950/pdf - Page: https://openairdocs.org/ntsb/MIA96LA028 ## Probable cause 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, approach - aircraft preflight - inadequate, pilot in command (contributing factor) - weather condition - carburetor icing conditions (contributing factor) - anti-ice/deice system,carburetor/heat - incorrect (cause) - maintenance,annual inspection - inadequate, other maintenance personnel (cause) - fuel system,carburetor - ice (cause) - checklist - not used, pilot in command - carburetor heat - not used, pilot in command - Forced landing, emergency descent/landing - In flight collision with object, emergency descent/landing - object - wire,transmission - Hard landing, emergency descent/landing ## Analysis 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. ## Factual narrative On November 15, 1995, about 1100 eastern standard time, a Bell 47D1, N4702S, registered to a private owner, operating as a 14 CFR Part 137 aerial application flight, without having been issued an FAA Part 137 certificate or operating specifications, experienced a partial loss of engine power on landing, and crashed in the vicinity of Jasper, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter sustained substantial damage. The commercial pilot reported no injuries. The flight originated about 15 minutes before the accident. The pilot stated he was returning to a field site to pick up chemicals. The before landing check was completed without the aide of a checklist, and he did not turn the carburetor heat on. He planned his approach to an open field bordered by houses on both sides, and a power line that crossed the final approach path. He started his descent at about 100 feet agl and 50 knots, when the engine experienced a partial loss of engine power. He felt he had sufficient altitude to clear the power lines. The engine sputtered, rotor rpm decayed, and manifold pressure decreased. He lowered the collective pitch and rolled the throttle to the full on position. The skids of the helicopter collided with the power line and separated. He lowered the collective pitch to full down position. No forward application of cyclic was applied. The helicopter descended vertically. Full up collective pitch was applied at about 3 feet, and the helicopter collided with the ground. Review of the aircraft log books revealed the last annual inspection was conducted on August 6, 1995. Examination of the engine assembly and accessories by Gulf Coast Helicopters Inc., Panama City, Florida, revealed no evidence of a precrash failure. Compression was found on all cylinders using a pressure differential check. The helicopter was equipped with a Marvel Schebler carburetor, part number 10-4025-12. The carburetor was not approved for use by the Franklin Engine Company. An incorrect spring was installed on the carburetor heat control valve and the carburetor heat could not be activated from the cockpit. (See Gulf Coast Helicopters. Inc., statement.) Review of the probability icing chart revealed that the engine would encounter icing at glide and cruise power based on the weather observation at the time of the accident. ## Aircraft - Registration: [N4702S](https://openairdocs.org/aircraft/N4702S), registered now, S/N B-101R (OpenAirDocs) - Reported make and model: BELL 47-D1 - Registry model: [Bell 47D1](https://openairdocs.org/model/bell-47d1) (registry code 1180802) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Helicopter - Serial number: B-101R - Engines: FRANKLIN 6V335 210 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Holly A. Mullis - Airworthiness certificate: Standard, Normal - Departed: NONE, FL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 27; private, commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 531 total, 412 in this make and model, 475 as pilot in command, 106 in the last 90 days, 31 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 8 knots - Visibility: 7 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point 25 °F - Altimeter: 30.00 inHg - Observed at: VAD, 35 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19951115041659A](https://openairdocs.org/incident/19951115041659A), Nov 15, 1995: Bell 47D1, Jasper, FL, Substantial damage. Lost partial power landing. Settled into powerline. Fell vertical to ground. Carb heat exterior operated. Not on. ## Other investigations on N4702S (4) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB MIA02LA154](https://openairdocs.org/ntsb/MIA02LA154), Aug 20, 2002: Bell 47-D1 (N4702S), Union, SC, substantial damage. Probable cause: the pilot's failure to maintain obstacle clearance. - [NTSB MIA98LA230](https://openairdocs.org/ntsb/MIA98LA230), Aug 29, 1998: Bell 47D1 (N4702S), Dawson, GA, substantial damage. Probable cause: The pilot's selection of unsuitable terrain for landing resulting in debris being blown up during landing resulting in damage to the tail rotor and loss of control. - [NTSB LAX78FUQ25](https://openairdocs.org/ntsb/LAX78FUQ25), May 4, 1978: Bell 47G (N4702S), Sylmar, CA, substantial damage - [NTSB LAX71FUQ33](https://openairdocs.org/ntsb/LAX71FUQ33), Oct 20, 1970: Bell 47G (N4702S), Van Nuys, CA, substantial damage From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.