CEN09LA602 · Air Tractor Inc AT-301A
JP'S Agricair Air Tractor Inc AT-301A · Accident: powerplant system/component malfunction/failure while maneuvering
From Bancroft, WI (private airstrip) to Bancroft, WI (private airstrip)
Narrative check · The NTSB narrative appears to contradict this record's departure or destination. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- CEN09LA602
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Air Tractor Inc AT-301A
- Aircraft type
- Air Tractor AT-301
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N3651R
- Operator
- JP'S Agricair
- Onboard fatalities
- Unknown
- Route Narrative disagrees
- From Bancroft, WI (private airstrip)To Bancroft, WI (private airstrip)
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 137: Agricultural
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · low-altitude flying
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Powerplant system/component malfunction/failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
Approximate · Coordinates from the NTSB case API, not marked as estimated; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN09LA602
- Event ID
- 20090924X21103
- Case number
- CEN09LA602
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: d6452013356c4fabfbbd2e40a3afc07174035782651aedcc8c7973db4c8ce2b4; retrieved 2026-09-15T13:20:36.412Z.