# NTSB FTW94LA193: Bell 47H-1, N2831B, Tulsa, OK, June 4, 1994

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 4, 1994, 09:00 local (14:00 UTC)
- Place: Tulsa, OK
- Coordinates: 36.179744, -96.049652 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=36.1797&lon=-96.0497&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report November 14, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 19083
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW94LA193
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19083/pdf
- Page: https://openairdocs.org/ntsb/FTW94LA193

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN ROTOR RPM, HIS DELAYED LANDING FLARE, AND THE IMPROPER TOUCHDOWN.

## Sequence of events

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

- Hard landing, landing - flare/touchdown
  - emergency procedure - simulated, pilot in command
  - rotor rpm - not maintained, pilot in command (cause)
  - flare - delayed, pilot in command (cause)
  - touchdown - improper, pilot in command (cause)
  - misc rotorcraft,tail boom - separation

## Analysis

A HELICOPTER PRIVATE PILOT LANDED HARD DURING THE SIXTH PRACTICE AUTOROTATION OF THE DAY. THE LANDING FLARE WAS DELAYED AND THE MAIN ROTOR RPM DECAYED TO THE POINT THAT DURING TOUCHDOWN, THE MAIN ROTOR BLADES FLEXED DOWN AND IMPACTED THE TAILBOOM.

## Factual narrative

On June 4, 1994, at 0900 central daylight time, a Bell 47H-1 helicopter, N2831B, was substantially damaged while landing near Tulsa, Oklahoma.  The private pilot and his pilot rated passenger were not injured.  Visual meteorological conditions prevailed for the personal flight.

The pilot told the Federal Aviation Administration (FAA) inspector that during the sixth practice autorotation being performed to an open field adjacent to the Downtown Airport, the rotor RPM decayed and the helicopter landed hard.  The main rotor blades flexed down and chopped the tailboom.

## Aircraft

- Registration: [N2831B](https://openairdocs.org/aircraft/N2831B), registered now, S/N 1361, built 1957 (OpenAirDocs)
- Reported make and model: BELL 47H-1
- Registry model: [Bell 47H-1](https://openairdocs.org/model/bell-47h-1) (registry code 1181011) (OpenAirDocs)
- Registry engine: [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series) (registry code 27033, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1361
- Airframe hours: 6923
- Engines: FRANKLIN 6V-350A 235 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Turner, Terry J.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, December 23, 1993, 68 hours before
- Destination: 5F2

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: right; flight hours: 202 total, 106 in this make and model, 91 as pilot in command, 19 in the last 90 days, 8 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 64 °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 19940604014999A](https://openairdocs.org/incident/19940604014999A), Jun 4, 1994: Bell 47H1, Tulsa, OK, Substantial damage. During practice autorotations to a field allowed rotor RPM decay. Landed hard. Main rotors flexed. Chopped tailboom

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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