Probable cause
Fracture of the compressor turbine (CT) blades due to creep.
NTSB analysis
During departure climbout for spray operations, the pilot heard a “pop” and observed white smoke trailing the airplane. The pilot made a forced landing, during which the airplane struck an airport perimeter fence that resulted in substantial damaged to both wings.
Examination revealed that all compressor turbine (CT) rotor blades were fractured at varying spanwise locations. The power turbine (PT) rotor blades downstream of the CT blades exhibited impact damage and were fractured at varying spanwise locations.
Metallurgical analysis of the CT blades revealed micro-voids were present along the material grain boundaries and rafting of the gamma prime which were indicative of creep. Metallurgical analysis of the CT blades revealed solutioning of the gamma prime which is consistent with exposure to temperature in excess of the engine operating limits. It was not determined if the exposure to elevated temperatures occurred before or during the event.
Text from the NTSB. Open the NTSB docket for CEN22LA312 for the full record.
Event
- Date
- Jul 11, 2022
- Type
- Accident
- Place
- Decatur, Illinois
- Nearest airport
- Decatur Airport (DEC)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Air Tractor Inc AT-502B
- N-number
- N5850R
- Category
- Airplane
- Year built
- 2004
- 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.