# NTSB DEN88GA088: Bell 47G-3B1, N7863S, Gobernador, NM, March 21, 1988

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: March 21, 1988, 10:00 local (17:00 UTC)
- Place: Gobernador, NM
- Coordinates: 36.800239, -107.609878 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=36.8002&lon=-107.6099&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report April 25, 1989
- Report: Approved by Office Director
- NTSB case key (mKey): 17389
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN88GA088
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17389/pdf
- Page: https://openairdocs.org/ntsb/DEN88GA088

## Sequence of events

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

- Airframe/component/system failure/malfunction, hover
  - rotor drive system,freewheeling sprag unit - worn (cause)
  - rotor rpm - not maintained, pilot in command (cause)
  - rotor drive system,freewheeling sprag unit - disengaged (cause)
- Forced landing, descent - emergency
  - autorotation - attempted
- Hard landing, landing - flare/touchdown
  - flight controls - improper use of, pilot in command (contributing factor)

## Analysis

THE COMMERICAL PLT WAS HOVERING OUT OF GROUND EFFECT AT 40 FEET AGL. DURING A MANEUVER HE REPORTED HEARING A LOUD BANG AND THE ROTOR RPM BEGAN TO DECAY. THE PLT MADE A HOVERING AUTOROTATION RESULTING IN A HARD LANDING. THE MAIN ROTOR STRUCK THE TAIL BOOM AND SEVERED IT. A POST ACCIDENT TRANSMISSION TEAR DOWN REVEALED THAT THE LOCKING ROLLERS IN THE FREE WHEELING UNIT HAD WORN BEYOND TOLERANCE, ALLOWING THE MAIN ROTOR TO BECOME AND REMAIN DISENGAGED FROM THE TRANSMISSION.

## Aircraft

- Registration: [N7863S](https://openairdocs.org/aircraft/N7863S), registered now, S/N 6630 (OpenAirDocs)
- Reported make and model: BELL 47G-3B1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Category: Helicopter
- Serial number: 6630
- Airframe hours: 5024
- Engines: LYCOMING TVO-435-B1A 270 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Registered owner: James S. Hicks
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, February 20, 1988, 1 hours before
- Departed: GOBERNADOR, NM

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 49; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 17,460 total, 12,147 in this make and model, 155 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 70 °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 19880321008439A](https://openairdocs.org/incident/19880321008439A), Mar 21, 1988: Bell 47G3B1, Gobernador, NM, Substantial damage. Loud bang while herding horses. Autorotated to hard landing. Chopped tail off. Free wheeling unit worn beyond use.

## Other investigations on N7863S (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 DEN81FTE50](https://openairdocs.org/ntsb/DEN81FTE50), Jul 1, 1981: Bell 47G3B1 (N7863S), Salida, CO, 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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