# Accident 20041121032159A: Amtr SONEX, Oconomowoc, WI, November 21, 2004

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: November 21, 2004, 14:35 local time
- Place: Oconomowoc, WI
- Damage: Substantial damage
- Phase of flight: Fcd/Prec Ldg From Cruise
- Operating rules: General operating rules (Part 91)
- Location: 43.1094° N, 88.4861° W: From the FAA
- Nearby events: https://openairdocs.org/map.md?lat=43.1094&lon=-88.4861&mi=10
- Aircraft: N478SX, registered now (https://openairdocs.org/aircraft/N478SX) (OpenAirDocs)
- Registry model: Olson Harold D SONEX (registry code 05617FQ, https://openairdocs.org/model/olson-harold-d-sonex) (OpenAirDocs)
- Registry engine: Amateur-built UNKNOWN ENG (registry code 99999, https://openairdocs.org/engine/amateur-built-unknown-eng) (OpenAirDocs)
- Reported make and model: AMTR SONEX
- Reported engine: AMTRVW VW2180
- Fatal injuries: 0
- Pilot flight hours: 582 total, 45 in this make and model, 35 in the last 90 days
- NTSB investigation: [NTSB CHI05CA032](https://openairdocs.org/ntsb/CHI05CA032) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/20041121032159A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

(-23) ON NOVEMBER 21, 2004, AT 1435 CST, AN AMATEUR BUILT SONEX AIRCRAFT, VOLKSWAGEN POWERED, N478SX REGISTERED TO, BUILT BY AND PILOTED BY^PRIVACY DATA OMIT^EXPERIENCED AN ENGINE ROUGHNESS AND THEN FAILURE WHILE CRUISING AT 3000 FEET. THE SUBSEQUENT FORCED LANDING RESULTED IN A COLLSION WITH A CREEK BANK DURING WHICH THE AIRCRAFT FLIPPED OVER AND CAME TO REST ONE HALF MILE NORTHWEST OF THE OCONOMOWOC AIRPORT, OCONOMOWOC, WISCONSIN. VISUAL METEOROLOGICAL CONDITIONS PREVAILED AT THE TIME OF THE LOCAL PLEASURE FLIGHT. A VFR FLIGHT PLAN WAS NOT FILED. THE AIRCRAFT WAS SUBSTANTIALLY DAMAGED, AND THE PILOT ^PRIVACY D^ SUFFERED SERIOUS INJURIES. THE FLIGHT ORIGINATED AT WATERTOWN, WISCONSIN ON NOVEMBER 21, 2002 AT APPROXIMATELY 1400 CST.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CHI05CA032](https://openairdocs.org/ntsb/CHI05CA032), Nov 21, 2004: Olson Sonex (N478SX), Oconomowoc, WI, substantial damage. Probable cause: The loss of engine power due to a fatigue fracture of the crankshaft. An additional cause to the accident was the pilot/builder's failure to verify the dimensions of the shrink-fit crankshaft…

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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