# NTSB ATL89DLT03: Bell 47, N908B, Shelbyville, TN, May 12, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: May 12, 1989, 15:00 local (20:00 UTC)
- Place: Shelbyville, TN
- Coordinates: 35.489189, -86.440841 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4892&lon=-86.4408&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 30, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 7844
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL89DLT03
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/7844/pdf
- Page: https://openairdocs.org/ntsb/ATL89DLT03

## Probable cause

FAILURE IN THE ROTOR DRIVE SYSTEM FOR UNKNOWN REASONS. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT'S INABILITY TO PERFORM AN AUTOROTATION.

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering - aerial application
  - rotor drive system - undetermined (cause)
- Hard landing, descent - emergency
  - autorotation - attempted, pilot in command
  - autorotation - not possible, pilot in command (contributing factor)

## Analysis

INVESTIGATION REVEALED THAT THE HELICOPTER WAS ENGAGED IN AERIAL APPLICATION. DURING A PROCEDURE TURN AROUND THERE WAS A LOUD EXPLOSIVE NOISE & ENGINE RPM EXCEEDED ROTOR RPM. THE PILOT REDUCED THE THROTTLE & TRIED TO ENTER AN AUTOROTATION. ROTOR RPM HAD DECAYED & A HARD LANDING RESULTED. MOST PROBABLE CAUSE FOR THE LOSS OF ROTOR RPM WAS A DISCONNECT BETWEEN THE ENGINE & THE MAIN ROTOR FOR UNKNOWN REASONS.

## Aircraft

- Registration: [N908B](https://openairdocs.org/aircraft/N908B), registered now, S/N 479, built 1952 (OpenAirDocs)
- Reported make and model: BELL 47
- Registry model: [Bell 47D1](https://openairdocs.org/model/bell-47d1) (registry code 1180802) (OpenAirDocs)
- Registry engine: [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series) (registry code 27033, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 479
- Engines: LYCOMING VO-435-A1B reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: L. Lanier, doing business as Valley Flying Service
- Registered owner: Unknown
- Airworthiness certificate: Special, Restricted (Special)

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; commercial; airplane ratings: single-engine sea; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 9,000 total, 1,000 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 81 °F, dew point -0 °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 19890512011449A](https://openairdocs.org/incident/19890512011449A), May 12, 1989: Bell 47D1, Shelbyville, TN, Substantial damage. Loud bang engine RPM at red line. Shut down but too low for autorotation. Impact chopped tailboom. No cause given.

## Other investigations on N908B (7)

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 ATL97LA121](https://openairdocs.org/ntsb/ATL97LA121), Aug 11, 1997: Bell 47-D1 (N908B), Holcomb, MS, substantial damage. Probable cause: The failure of the pilot to adequately see and avoid all obstructions while doing aerial application work.
- [NTSB ATL94LA172](https://openairdocs.org/ntsb/ATL94LA172), Sep 13, 1994: Bell 47D1 Wasp (N908B), Hazel Green, AL, substantial damage. Probable cause: UNDETERMINED.
- [NTSB ATL87LA204](https://openairdocs.org/ntsb/ATL87LA204), Jul 8, 1987: Bell 47D1 (N908B), Huntsville, AL, substantial damage
- [NTSB MIA79FLA48](https://openairdocs.org/ntsb/MIA79FLA48), Sep 1, 1979: Bell 47D1 (N908B), Hahira, GA, destroyed
- [NTSB MIA77DKG41](https://openairdocs.org/ntsb/MIA77DKG41), Jul 2, 1977: Bell 47-D1 (N908B), Berlin, GA, substantial damage
- [NTSB MKC76DCQ57](https://openairdocs.org/ntsb/MKC76DCQ57), Jun 4, 1976: Bell 47D-1 (N908B), Sublette, KS, substantial damage
- [NTSB MIA72FLG08](https://openairdocs.org/ntsb/MIA72FLG08), Aug 14, 1971: Bell 47D-1 (N908B), Cheraw, SC, 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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