# NTSB FTW84LA325: Bell 47J, N2837B, Grove, OK, July 27, 1984

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: July 27, 1984, 10:30 local (15:30 UTC)
- Place: Grove, OK
- Coordinates: 36.58971, -94.779487 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=36.5897&lon=-94.7795&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21410
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW84LA325
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21410/pdf
- Page: https://openairdocs.org/ntsb/FTW84LA325

## Sequence of events

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

- Airframe/component/system failure/malfunction, takeoff - initial climb
  - rotor drive system,tail rotor drive shaft - separation (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
  - rotorcraft flight control,tail rotor control - loss,total (cause)
  - directional control - not possible, pilot in command (cause)
  - autorotation - attempted, pilot in command
- Forced landing, descent - emergency
  - directional control - not possible, pilot in command
- Roll over, landing - flare/touchdown
  - terrain condition - high obstruction(s)
- Fire/explosion, other

## Analysis

THE PLT STATED THAT YAW CONTROL WAS LOST DURING CLIMB OUT FOR A LOCAL FLT WITH TWO PASSENGERS ONBOARD. THE ACFT BEGAN TOROTATE TO THE RIGHT AND THE ANTITORQUE PEDALS WERE INEFFECTIVE. THEY WERE OVER BUILDINGS AT THE TIME SO THE PLT HELD A MINIMUM DESCENT UNTIL CLEAR OF THE BUILDINGS. THE ACFT CONTINUED TO ROTATE UNTIL GROUND IMPACT. THE ACFT ROLLED OVER ON ITS RIGHT SIDE AND CAUGHT FIRE. INSPECTION OF THE ACFT REVEALED THAT BOTH PINS IN THE TAIL ROTOR DRIVE U-JOINT HAS SHEARED DUE TO UNSUFFICIENT TORQUE ON THE ACORN NUTS.

## Aircraft

- Registration: N2837B (not matched to a registry record)
- Reported make and model: BELL 47J
- Category: Helicopter
- Serial number: 1720
- Airframe hours: 3493
- Engines: LYCOMING VO-435-A1E 260 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Personal, Part 91
- Registered owner: Ol' Country Boy, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, April 12, 1984, 20 hours before
- Departed: GROVE, OK

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; airline transport, flight instructor; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: helicopter, airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; toxicology performed; flight hours: 7,580 total, 400 in this make and model, 7,400 as pilot in command, 50 in the last 90 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 10° at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 81 °F, dew point 68 °F
- Altimeter: 30.00 inHg

## 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 19840727035729A](https://openairdocs.org/incident/19840727035729A), Jul 27, 1984: Bell 47J, Grove, OK, Destroyed. Crash occured during emergency landing after tail rotor drive u joint had sheared.

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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