CEN24LA193 · Air Tractor Inc AT-502
Air Tractor Inc AT-502 · Accident: powerplant system/component malfunction/failure while maneuvering
From Osborne Municipal Airport (K75) to an unrecorded destination
Event
- NTSB case
- CEN24LA193
- 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
- Event fatalities
- Unknown
- 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-502
- Aircraft type
- Air Tractor AT-502
- 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
- N15189
- Operator
- Tri Rotor Spray & Chemical
- Onboard fatalities
- Unknown
- Route
- From Osborne Municipal Airport (K75), Osborne, KSTo not recorded
- Aircraft age
- About 33 years (built 1991)
- 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
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During an agricultural application flight, the pilot noticed a loss of thrust and adjusted engine power as needed. The subsequent application pass was normal; however, while turning the airplane around for another pass, he felt the “tail drop” and noticed that several engine gauges had exceeded limitations. The pilot attempted to reduce engine power but found that the engine was unresponsive to power control inputs and that the airplane was unable to maintain altitude. He chose to land on a nearby gravel road, during which the airplane impacted tree branches and ground looped into a ditch, resulting in substantial damage to both wings. After the airplane came to rest, the engine continued to run until the pilot cut off the fuel supply. Postaccident examination of the engine revealed an improperly torqued and safety wired P3 adapter on the fuel control unit (FCU). This allowed the two attachment screws, used to secure the P3 adapter to the main body of the FCU, to back off, which resulted in excessive air leakage and movement of the gasket between the adapter and the FCU main body. This leakage fluctuated when light finger pressure was applied to the P3 adapter that connected to the FCU main body. The P3 adapter’s seal with the FCU’s main body likely degraded over time because the screws backed off, allowing relative motion between the gasket and sealing surfaces. The intermittent air leakage compromised FCU fuel control capability, likely resulting in the FCU’s fuel flow metering valve to move to its minimum setpoint and the erratic engine behavior observed by the pilot. The date that the accident FCU was installed on the accident engine could not be determined based on maintenance records. The only entry indicating this FCU’s condition was on August 25, 2022, and noted that the FCU was already installed on the engine when received and was in serviceable condition during final inspection. The only maintenance performed on this FCU while installed on the accident airplane was changing the fuel filter.
Probable cause
The improper maintenance of the fuel control unit, which resulted in air leakage and a loss of control of fuel flow to the engine.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN24LA193
- Event ID
- 20240520194284
- Case number
- CEN24LA193
- 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: local date, investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2024-05-19.
- API snapshot SHA-256: 75a380a3212efffec5f618c70b65aca31ba95285f9b70977da30af52f80c60f7; retrieved 2026-09-16T18:46:51.985Z.