# NTSB SEA78FTA08: Bell 47G3B1, N7860S, Billings, MT, December 20, 1977

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Closed
- Date: December 20, 1977
- Place: Billings, MT · BILLINGS, MT
- Location: 45.7833° N, 108.5007° W: Placed by OpenAirDocs: center of Billings, MT, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=45.7833&lon=-108.5007&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 2 minor, 1 uninjured
- Status: Completed, report April 17, 1978
- Report: Brief approved by the director
- NTSB case key (mKey): 144084
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA78FTA08
- Page: https://openairdocs.org/ntsb/SEA78FTA08

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
3-4182  77/12/20 NR.BILLINGS,MT        BELL 47G3B1         CR-  0  0  1  NONCOMMERCIAL             AIRLINE TRANSPORT, AGE
        TIME - 1500                    N7860S              PX-  0  0  2  BUSINESS                  45, 17500 TOTAL HOURS,
                                       DAMAGE-DESTROYED    OT-  0  0  0                            700 IN TYPE, NOT
                                                                                                   INSTRUMENT RATED.
        DEPARTURE POINT             INTENDED DESTINATION
         BILLINGS,MT                  LOCAL
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           PROPELLER/ROTOR FAILURE: MAIN ROTOR                      IN FLIGHT: NORMAL CRUISE
           HARD LANDING                                             LANDING: POWER-OFF AUTOROTATIVE LANDING
        PROBABLE CAUSE(S)
           ROTORCRAFT - TRANSMISSION ROTOR DRIVE SYSTEM: OTHER
           MISCELLANEOUS ACTS,CONDITIONS - IMPROPER CLEARANCE-TOLERANCE
           MISCELLANEOUS ACTS,CONDITIONS - EXCESSIVE-WEAR/PLAY
           MISCELLANEOUS ACTS,CONDITIONS - IMPROPERLY INSTALLED
           PERSONNEL - MAINTENANCE,SERVICING,INSPECTION: INADEQUATE MAINTENANCE AND INSPECTION
        EMERGENCY CIRCUMSTANCES - FORCED LANDING OFF AIRPORT ON LAND
                                  UNUSUAL NOISE
        REMARKS- ATTMTD AUTOROTATION DUE LOUD NOISE. COLLECTIVE WAS INOP. WRONG TRANSMISSION INSTALLED.
```

## Aircraft

- Registration: [N7860S](https://openairdocs.org/aircraft/N7860S), registered now, S/N 6627 (OpenAirDocs)
- Reported make and model: BELL 47G3B1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Registry engine: [Allison 250 series](https://openairdocs.org/engine/allison-250-series) (registry code 03019, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Engines: reciprocating
- Damage: Destroyed

## 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 19771220038559A](https://openairdocs.org/incident/19771220038559A), Dec 20, 1977: Bell 47G3B1, Billings, MT, Destroyed. Attmtd autorotation due loud noise. Collective was inop. Wrong transmission installed.

## Other investigations on N7860S (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 WPR10CA470](https://openairdocs.org/ntsb/WPR10CA470), Sep 26, 2010: Bell 47G (N7860S), Gaston, OR, substantial damage. Probable cause: The pilot's failure to maintain tail rotor clearance while landing on a transport trailer positioned on an uneven surface.

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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