Probable cause
The loss of engine power during takeoff due to the fatigue failure of the turbine wheel blades, which resulted from inadequate maintenance and inspections.
NTSB analysis
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.
Text from the NTSB. Open the NTSB docket for WPR11LA386 for the full record.
Event
- Date
- Aug 16, 2011
- Type
- Accident
- Place
- Hardin, Montana
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Air Tractor Inc AT-401
- N-number
- N1012T
- Category
- Airplane
- Damage
- Substantial
- Operating rule
- Part 137 (agricultural)
- Purpose of flight
- Aerial application
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.