# NTSB FTW87LA107: Bell 47D1, N3575, Ardmore, OK, April 25, 1987

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 25, 1987, 17:30 local (22:30 UTC)
- Place: Ardmore, OK
- Coordinates: 34.19057, -97.110824 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.1906&lon=-97.1108&mi=10
- Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report March 30, 1988
- Report: Approved by Office Director
- NTSB case key (mKey): 22356
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW87LA107
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22356/pdf
- Page: https://openairdocs.org/ntsb/FTW87LA107

## Sequence of events

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

- Forced landing, descent - emergency
  - precautionary landing - performed, pilot in command
  - autorotation - performed, pilot in command
- Hard landing, landing - flare/touchdown
  - terrain condition - rough/uneven
  - flare - inadequate, pilot in command (cause)

## Analysis

THE PILOT REPORTEDLY HEARD AN UNUSUAL NOISE IN THE ENGINE AND MADE A PRECAUTIONARY AUTOROTATION TO LANDING. TOUCHDOWN WAS ON UNEVEN TERRAIN AND IN A NOSE LOW ATTITUDE. THIS RESULTED IN THE TAIL ROTOR ASSEMBLY BEING CHOPPED OFF THE TAIL BOOM BY THE MAIN ROTOR BLADES. AFTER RECOVERY THE OWNER/OPERATOR STATED HE FOUND NO EVIDENCE OF ANYTHING OTHER THAN A HARD LANDING WHICH RESULTED IN THE MAIN ROTOR BLADES MAKING CONTACT WITH THE TAIL BOOM AND CHOPPING IT IN TWO.

## Aircraft

- Registration: [N3575](https://openairdocs.org/deregistered/N3575-2021-03-06), registration cancelled 2021-03-06, S/N K-7032 (OpenAirDocs)
- Reported make and model: BELL 47D1
- Registry model: [Bell 47D1](https://openairdocs.org/model/bell-47d1) (registry code 1180802) (OpenAirDocs)
- Registry engine: [Franklin 6V-335 series](https://openairdocs.org/engine/franklin-6v-335-series) (registry code 27039, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: K-7032
- Airframe hours: 4000
- Engines: FRANKLIN O-335-5D 165 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Versatile Aviation
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 1, 1987, 40 hours before
- Departed: 1F0, ARDMORE, OK
- Destination: 1F0, ARDMORE, OK

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 24; commercial, private; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 520 total, 394 in this make and model, 417 as pilot in command, 75 in the last 90 days, 7 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 160° at 5 knots
- Visibility: 5 statute miles
- Lowest ceiling: none
- Altimeter: 29.00 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 19870425021269A](https://openairdocs.org/incident/19870425021269A), Apr 25, 1987: Bell 47D1, Ardmore, OK, Substantial damage. The helicopter landed hard causing rotor to strike tailboom. Pilot suspected engine problems and autorotated.

## Other investigations on N3575 (3)

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 FTW91LA126](https://openairdocs.org/ntsb/FTW91LA126), Jul 24, 1991: Bell 47D-1 (N3575), Provencal, LA, substantial damage. Probable cause: FUEL LEAKAGE FROM THE FUEL DRAIN VALVE. A FACTOR WAS THE INACCESSIBILITY OF SUITABLE TERRAIN FOR FORED LANDING.
- [NTSB FTW79DPJ37](https://openairdocs.org/ntsb/FTW79DPJ37), Sep 12, 1979: Bell 47D1 (N3575), Ardmore, OK, substantial damage
- [NTSB MIA77DKG08](https://openairdocs.org/ntsb/MIA77DKG08), Dec 12, 1976: Bell 47D1 (N3575), Vanceville, GA, 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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