Air Tractor INC AT-401 accident near Hardin, Montana, August 16, 2011
On August 16, 2011 at about 3:00 pm local time, a Air Tractor INC AT-401, registered N1012T, was substantially damaged in an accident during takeoff near Hardin, Montana. 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
The loss of engine power during takeoff due to the fatigue failure of the turbine wheel blades, which resulted from inadequate maintenance and inspections.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 16, 2011 · about 3:00 pm local time
- Place
- Hardin, Montana · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor INC AT-401 · all AT-401s on the register
- Registration
- N1012T · registry record · serial 401-0719
- 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 that, shortly after takeoff for the aerial application flight, the engine quit. He did not have sufficient altitude to restart the engine, so he made a forced landing to an open field; the airplane came to rest upright, and the airframe sustained structural damage. A visual examination of the engine at the accident site revealed that the compressor section had sustained fire damage and that the turbine section had broken and missing vanes. Postaccident metallurgical examination revealed that one of the turbine wheel blades had fractured and that the fracture surfaces revealed signatures consistent with fatigue propagation and subsequent failure. About 1 year 5 months before the accident, an examination of the engine revealed excessive wear to the combustor outer liner lugs, and the engine was determined to be unserviceable. About 1 year 1 month later (about 4 months before the accident), the airplane underwent a 100-hour inspection and was returned to service in an airworthy condition. No evidence was found indicating that the engine was overhauled or replaced during the 1-year period between when it was determined to be unserviceable and when it was returned to service. The pilot reported that the airplane had undergone a 100-hour inspection 1 week before the accident, but no entries were found pertaining to the inspection in the airplane's maintenance logbooks. The engine had accrued 2,819.6 hours since major overhaul. No evidence was found indicating that the engine was inspected in accordance with the manufacturer's recommended time between overhaul inspection interval of 2,000 hours. It is likely that proper maintenance inspections would have detected the crack and wear in the engine.
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
- Loss of engine power (partial) during takeoff defining event
- Collision with terrain or object (not controlled flight into terrain) during emergency descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Turbine section › Fatigue/wear/corrosion
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Not serviced/maintained
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Inadequate inspection
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land
- Flight time: 15,600 hours in all; 5,000 in this make and model
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Airframe total time: 7,300 hours
- Last inspection: annual inspection, April 19, 2011; 295.4 hours since
- Seats: 1
- Landing gear: fixed
- Engine: Ge Aviation Czech M601E-11 (turboprop); 0 hours total
The flight
- Departed from: Hardin MT
- Destination: Hardin MT
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: a few clouds at 9,000 ft
- Temperature: 61°F (16°C), dew point 52°F (11°C)
- Altimeter: 30.17 inHg
- Observation at 3:00 pm from BIL, 39 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.