Bell 47 accident near Shelbyville, Tennessee, May 12, 1989
On May 12, 1989 at about 8:00 pm local time, a Bell 47 (helicopter), registered N908B, was substantially damaged in an accident near Shelbyville, Tennessee. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
FAILURE IN THE ROTOR DRIVE SYSTEM FOR UNKNOWN REASONS. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT'S INABILITY TO PERFORM AN AUTOROTATION.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 12, 1989 · about 8:00 pm local time
- Place
- Shelbyville, Tennessee · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47 · all 47s on the register
- Registration
- N908B · registry record · serial 479
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: single-engine sea; rotorcraft: helicopter
- Flight time: 9,000 hours in all; 1,000 in this make and model
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
The aircraft
- Last inspection: inspection type not recorded; 0 hours since
- Maximum gross weight: 3,000 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming VO-435-A1B (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N908B the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.