CHI07LA173 · Air Tractor AT-301
Air Tractor AT-301 · Accident: airframe, component or system failure en route
From Fergus Falls Municipal Airport - Einar Mickelson Field (FFM) to an unrecorded destination
Event
- NTSB case
- CHI07LA173
- 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 AT-301
- Aircraft type
- Air Tractor AT-301
- 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
- N23667
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Fergus Falls Municipal Airport - Einar Mickelson Field (FFM), Fergus Falls, MNTo 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
- En route · climb to cruise
- 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
- Airframe, component or system 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
- Propeller system/accessories, blade › Failure
- Propeller system/accessories, blade › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The agricultural spray airplane sustained substantial damage during a forced landing following a severe engine vibration during cruise flight. The pilot reported that he was in cruise flight about 500 feet above ground level (agl) when the engine and airframe started to vibrate violently, and the windshield became covered with oil. He made a forced landing to a field, but the main landing gear broke off and the airplane flipped over. Inspection of the airplane revealed that one of the propeller blades was missing about 9 inches of the propeller blade tip. The propeller blade was cut and the piece with the fracture surface was sent to the National Transportation Safety Board's Materials Laboratory for examination. The inspection of the fracture surface revealed that the propeller bladed failed as a result of a fatigue crack, with features typical of impact of a rotating propeller blade with a foreign object. Aircraft maintenance records indicated that the propeller blade was repaired and overhauled on October 21, 2003. The overhaul documents indicated that the no discrepancies were found when the propeller blades and hub underwent visual and non-destructive testing. The aircraft operator reported that he had purchased the propeller blade from another operator as a "0" time blade since major overhaul. Since installing the propeller on the accident airplane, it had been flown for about 30 hours. The operator reported that the accident airplane did not have a propeller strike during the 30 hours of operation prior to the accident flight.
Probable cause
The propeller blade failure during climb due to a fatigue crack. The oil leak that obstructed the pilot's vision was a factor in the accident.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI07LA173
- Event ID
- 20070629X00850
- Case number
- CHI07LA173
- 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: 3370859f9961ebe53c6524c8360115ad46438e936a4d3f42c2c5fc26cd1c6383; retrieved 2026-09-21T18:29:08.150Z.