# NTSB FTW91DRD05: Bell 47-D1, N339MC, Sun, LA, May 26, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: May 26, 1991, 17:00 local (22:00 UTC)
- Place: Sun, LA
- Coordinates: 30.660148, -89.899299 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.6601&lon=-89.8993&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report May 3, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 23224
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW91DRD05
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23224/pdf
- Page: https://openairdocs.org/ntsb/FTW91DRD05

## Probable cause

THE TOTAL LOSS OF POWER FOR UNDETERMINED REASONS AND THE FAILURE OF THE PILOT TO MAINTAIN ROTOR RPM. A FACTOR WAS THE LACK OF SUITABLE TERRAIN.

## Sequence of events

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

- Loss of engine power, climb
  - powerplant - failure,total (cause)
  - reason for occurrence undetermined
  - load jettison - initiated, pilot in command
- Forced landing, descent - emergency
  - misc rotorcraft,tail boom - separation
  - rotor rpm - not maintained, pilot in command (cause)
  - terrain condition - none suitable (contributing factor)
- Hard landing, landing - flare/touchdown

## Analysis

THE PILOT HAD JUST DEPARTED A LOCAL FAIR GROUNDS WITH TWO PAYING PASSENGERS ON BOARD. AT APPROXIMATELY 300 FEET, A TOTAL LOSS OF ENGINE POWER WAS EXPERIENCED. THE PILOT INITIATED A 180 DEGREE AUTOROTATION IN ORDER TO CLEAR THE POPULATED AREA. THE AVAILABLE TERRAIN FOR LANDING WAS NOT LEVEL. DURING THE TOUCHDOWN, ROTOR RPM DECREASED DUE TO THE DIFFICULTY OF CONDUCTING A SLOPE LANDING. THE MAIN ROTOR BLADES SEVERED THE TAILBOOM OF THE HELICOPTER

## Aircraft

- Registration: [N339MC](https://openairdocs.org/deregistered/N339MC-1996-07-25), registration cancelled 1996-07-25, S/N T121 (OpenAirDocs)
- Reported make and model: BELL 47-D1
- Registry model: [Bell 47D1](https://openairdocs.org/model/bell-47d1) (registry code 1180802) (OpenAirDocs)
- Category: Helicopter
- Serial number: T121
- Airframe hours: 5468
- Engines: FRANKLIN 6V335A 210 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial observation, Part 91
- Operator: Cook Aviation, Inc.
- Registered owner: Cook Aviation, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 6, 1991, 21 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 3,230 total, 397 in this make and model, 3,044 as pilot in command, 112 in the last 90 days, 49 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: 2,500 ft broken
- Temperature: 81 °F, dew point -0 °F

## 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 19910526017319A](https://openairdocs.org/incident/19910526017319A), May 26, 1991: Bell 47D1, Sun, LA, Substantial damage. Reported power failure on climbout. Autorotated to hard landing. No engine problems found.

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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