CHI03LA274 · Boeing A-75
Boeing A-75 · Accident: total loss of engine power (mechanical failure) on approach
From Lawrence J Timmerman Airport (MWC) to La Crosse Regional Airport (LSE)
Event
- NTSB case
- CHI03LA274
- 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
Boeing A-75
- Aircraft type
- Boeing A-75
- 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
- N806RB
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lawrence J Timmerman Airport (MWC), Milwaukee, WITo La Crosse Regional Airport (LSE), La Crosse, WI
- 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 91: General Aviation
- 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
- Approach · VFR pattern final
- 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
- Total 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
- Engine assembly, crankshaft › Failure, total
- Engine assembly, crankshaft › Fatigue
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The airplane sustained substantial damage when it nosed over during a forced landing to a cornfield after a total loss of engine power. The pilot reported the engine "suddenly began vibrating." The engine seized and the propeller stopped turning 10 seconds after the vibration started. He executed a forced landing to a cornfield, and the airplane nosed over during landing roll. The inspection revealed that the crankshaft was fractured in two pieces, with the fracture between the crankshaft rod journal and the front main bearing. Fatigue stress crack progression was observed on approximately 50 percent of the fracture surface. The cracking appeared to originate in the forward radius of the master-rod bearing journal. The remainder of the fracture surface exhibited conditions typical of tensile overload. The reason for the initiation of the crack in the journal radius of the crankshaft was not identified. The engine manufacturer's recommended time between overhaul (TBO) for the R-985 engine is 1,600 hours. The operator imposed a 1,200 hour TBO on the engines used in its fleet of airplanes.
Probable cause
The total loss of engine power due to a fatigue fracture of the engine's crankshaft. A factor was the corn crop.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI03LA274
- Event ID
- 20030822X01388
- Case number
- CHI03LA274
- 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, coordinates. 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: b43dc6c06bb711af376857a2ff09dddad938fbf45b323311f2821bceb430f196; retrieved 2026-09-22T08:41:47.889Z.