Air Tractor INC AT-301A accident near New Miner, Wisconsin, August 22, 2009
On August 22, 2009 at about 9:15 pm local time, a Air Tractor INC AT-301A, registered N3651R, was substantially damaged in an accident during maneuvering (low-alt flying) near New Miner, Wisconsin (Private airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A total loss of engine power due to the fatigue failure of the engine torsion shaft. Contributing to the accident was the chrome plating of the shaft by an undetermined maintenance/overhaul facility.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 22, 2009 · about 9:15 pm local time
- Place
- New Miner, Wisconsin · Private · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor INC AT-301A · all AT-301As on the register
- Registration
- N3651R · no longer on the register · serial 301-0261
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported a complete loss of engine power about 15 minutes after takeoff during an agricultural application pass. He executed a forced landing into a tree plantation adjacent to the agricultural field. A postaccident inspection of the engine revealed that the torsion shaft had separated near the forward bushing journal. The fracture surfaces exhibited features consistent with fatigue failure. In addition, chromium plating was observed at all three bearing journals. Further examination by NTSB materials engineers determined that the torsion shaft fractured due to fatigue that was likely initiated by cracks in the chromium plate repair of the shaft. The plating itself was porous with radial cracks at all journal locations. Records indicated that the torsion shaft was newly overhauled when it was installed in the engine, about 3 1/2 years prior to the accident. However, detailed records related to the overhaul work were not available and the source of the chrome plating could not be determined. The engine manufacturer stated that chrome plating was not specified for production parts, nor was it permitted during component overhaul. A service bulletin recommending replacement of the torsion shaft had not been completed. The bulletin recommended replacement of the original (long) torsion shaft with a shorter shaft. The bulletin noted that the long torsion shafts were susceptible to bushing and bushing journal wear, which would be reduced by installation of the short torsion shafts.
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
What happened, in order
- Powerplant sys/comp malf/fail during maneuvering (low-alt flying) defining event
- Loss of engine power (total) during maneuvering (low-alt flying)
- Off-field or emergency landing during emergency descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Reduction gear and shaft › Fatigue/wear/corrosion
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Reduction gear and shaft › Failure
- factor Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Reduction gear and shaft › Incorrect service/maintenance
- Personnel issues › Task performance › Maintenance › (general) › Not specified
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 5,500 hours in all; 1,500 in this make and model
- Last flight review: June 1, 2008
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: sngl
- Injury: minor injuries
The aircraft
- Airframe total time: 7,209 hours
- Last inspection: annual inspection, June 1, 2009
- Maximum gross weight: 6,308 lb
- Seats: 1
- Landing gear: fixed
- Engine: Honeywell TPE331-5-151A (turboprop); 0 hours total
- Operator: Jp'S Agricair INC
The flight
- Departed from: PVT Bancroft WI at 9:00 pm
- Destination: PVT Bancroft WI
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 330° at 6 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 4,100 ft
- Temperature: 70°F (21°C), dew point 52°F (11°C)
- Altimeter: 30.09 inHg
- Observation at 8:54 pm from ISW, 14 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.
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.