# NTSB ATL93LA009: Bell 47G-3B-1, N31FG, Centre, AL, October 9, 1992

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: October 9, 1992, 16:15 local (21:15 UTC)
- Place: Centre, AL
- Coordinates: 34.150562, -85.670158 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.1506&lon=-85.6702&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 21, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8692
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL93LA009
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8692/pdf
- Page: https://openairdocs.org/ntsb/ATL93LA009

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN MAIN ROTOR RPM, WHICH RESULTED IN AN IN FLIGHT LOSS OF CONTROL AND COLLISION WITH TERRAIN.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - in flight, maneuvering - turn to reverse direction
  - rotor rpm - not maintained, pilot in command (cause)
  - aircraft control - not maintained, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE AG PILOT REPORTED THAT WHILE PERFORMING A MANEUVER (TURN TO REVERSE DIRECTION), HE ALLOWED THE MAIN ROTOR RPM TO DECAY. HE LOST CONTROL OF THE HELICOPTER, AND IT BOUNCED INTO A FIELD. THE AIRCRAFT BECAME AIRBORNE AGAIN, AND THE RPM DECAYED ONCE MORE. THE HELICOPTER THEN CRASHED INTO THE FIELD, AND THE TAIL BOOM WAS SEVERED BY THE MAIN ROTOR BLADES DURING IMPACT. THE PILOT REPORTED NO MECHANICAL MALFUNCTION OR FAILURE WITH THE HELICOPTER DURING THE ACCIDENT FLIGHT.

## Aircraft

- Registration: [N31FG](https://openairdocs.org/aircraft/N31FG), registered now, S/N 3834, built 1968 (OpenAirDocs)
- Reported make and model: BELL 47G-3B-1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Registry engine: [Lycoming 0-435](https://openairdocs.org/engine/lycoming-0-435) (registry code 41516, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 3834
- Engines: LYCOMING TVO-435-B1A 270 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Speth, Stephen F.
- Registered owner: Coastal Helicopters, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Unknown, January 2, 2000
- Departed: A04, CENTRE, AL
- Destination: A04

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 3,400 total

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 4 knots
- Visibility: 7 statute miles
- Lowest ceiling: 20,000 ft broken
- Temperature: 52 °F, dew point 50 °F
- Altimeter: 30.00 inHg
- Observed at: ANB, 36 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 19921009045309A](https://openairdocs.org/incident/19921009045309A), Oct 9, 1992: Bell 47G3B1, Centre, AL, Substantial damage. Allowed rotor RPM decay on turn around. Settled to ground,bounced,no RPM increase impacted. Rotors chopped tail.

## Other investigations on N31FG (1)

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 MIA85LA224](https://openairdocs.org/ntsb/MIA85LA224), Aug 1, 1985: Bell TH-13T (N31FG), Quitman, GA, 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.

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