CHI95LA258 · Air Tractor AT-401
Air Tractor AT-401 · Accident: partial loss of engine power (mechanical failure) while maneuvering
From Aurora Municipal Al Potter Field (AUH) to an unrecorded destination
Event
- NTSB case
- CHI95LA258
- 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
- 0
- 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 AT-401
- 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
- N4543F
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Aurora Municipal Al Potter Field (AUH), NETo not recorded
- Aircraft age
- Not recorded
- 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 · aerial application
- First occurrenceThe 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
- Partial loss of engine power (mechanical 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
No findings designated as a cause are recorded in the NTSB data yet.
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
AT THE BEGINNING OF THE PILOT'S SWATH RUN HE NOTICED WHITE SMOKE COMING FROM THE RIGHT SIDE OF THE ENGINE. HE SAID HE DISCONTINUED THE RUN AND TURNED BACK TOWARD HIS HOME AIRPORT. JUST AS THE AIRPLANE LEVELED OUT FROM ITS TURN THE PILOT SAID THE ENGINE LOST MOST OF ITS POWER. THE PILOT SAID HE HEADED THE AIRPLANE FOR A PASTURE BUT WAS UNABLE TO GLIDE TO IT. THE AIRPLANE NOSED OVER SHORTLY AFTER ITS WHEELS CONTACTED THE CORN, COMING TO REST ON THE GROUND. EXAMINATION OF THE ENGINE REVEALED THE NUMBER 4 CYLINDER'S EXHAUST TOWER WAS CRACKED WHERE THE ROCKER ARM SHAFT WENT THROUGH THE CYLINDER HEAD. THE OWNER/MECHANIC OF THE AIRPLANE SAID THE CONDITION RESULTING FROM THE DAMAGED EXHAUST TOWER PREVENTS THE CYLINDER'S EXHAUST VALVE FROM OPENING. THE RESULT OF THE EXHAUST VALVE NOT OPENING CREATES A BLOW BACK CONDITION THAT AFFECTS THE OTHER CYLINDERS. THE END RESULT, ACCORDING TO THE OWNER, IS THAT THE ENGINE WILL LOSE MOST OF ITS POWER. THIS WAS CONFIRMED BY THE FAA PRINCIPAL MAINTENANCE INSPECTOR WHO CONDUCTED THE ENGINE EXAMINATION.
Probable cause
the cracked engine assembly that caused the power loss during a critical phase of flight. Factors associated with this accident were the restricted airplane performance due to the power loss, the airplane's altitude was too low, and remedial action, by, the pilot, that would lead to an uneventful forced landing was not possible.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI95LA258
- Event ID
- 20001207X04184
- Case number
- CHI95LA258
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: 1778e9fb6d3a0bc587e676d9ee1a887e357dfa80d09d140cd8cd5dac39e30d89; retrieved 2026-09-22T23:31:00.284Z.