CEN17LA330 · Air Tractor Inc AT 401 UNDESIGNAT
Fitch's Flying Service Air Tractor Inc AT 401 UNDESIGNAT · Accident: loss of engine power (partial) while maneuvering
From Mc Kinley Field (T30) to Mc Kinley Field (T30)
Event
- NTSB case
- CEN17LA330
- 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 401 UNDESIGNAT
- Aircraft type
- Air Tractor AT-401
- 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
- N4532F
- Operator
- Fitch's Flying Service
- Onboard fatalities
- Unknown
- Route
- From Mc Kinley Field (T30), Pearsall, TXTo Mc Kinley Field (T30), Pearsall, TX
- Aircraft age
- About 27 years (built 1990)
- 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
- Loss of engine power (partial)
- 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 as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The commercial pilot was conducting a local, agricultural application flight when the engine experienced a partial loss of power during a spray pass. The pilot's corrective actions did not restore normal engine operation, and he conducted a forced landing to a nearby field. The airplane descended into tall vegetation and landed in soft, sandy soil and then decelerated rapidly and nosed over.
Postaccident engine examination revealed a circumferential fracture of the No. 9 cylinder. Further examination determined that the cylinder fractured from a fatigue crack that had initiated at multiple locations at a valley between two cooling fins on the outside surface. The fatigue crack progressed inward and circumferentially around the cylinder before finally cracking in overstress. No discrepancies, such as corrosion pits, wear marks, or machining marks, were found at the crack initiation sites. The cylinder met the airplane manufacturer's material and hardness specifications. The fracture would have allowed combustion gasses to escape during engine operation and led to a corresponding loss of cylinder compression, which would have led to erratic engine operation and a partial loss of power. According to engine logbook documentation, no cylinder cracks were found during an airworthiness directive inspection completed about 64 flight hours before the accident.
Probable cause
The fatigue crack of an engine cylinder, which resulted in a partial loss of engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN17LA330
- Event ID
- 20170828X93014
- Case number
- CEN17LA330
- 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. 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: c194a751ce06c12db91e6d4656d7ea1af2ecf2bebe68ebd1ae528cf8717237f1; retrieved 2026-09-16T05:46:22.017Z.