Amateur-built CHALLENGER II accident near Praire Du Sac, Wisconsin, November 1, 2010
On November 1, 2010 at about 7:15 pm local time, a amateur-built CHALLENGER II, registered N448WM, was substantially damaged in an accident during enroute (cruise) near Praire Du Sac, Wisconsin. It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The separation of the fuselage-mounted wing strut attachment fitting for an undetermined reason, which resulted in the separation of the left wing of the airplane.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 1, 2010 · about 7:15 pm local time
- Place
- Praire Du Sac, Wisconsin · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built CHALLENGER II
- Registration
- N448WM · no longer on the register · serial CH2-1002-2263
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane impacted the ground following an in-flight separation of the left wing during cruise flight. The pilot, who was the sole occupant, was fatally injured. Witnesses reported seeing the airplane traveling north, about 300-500 feet above ground level, when one wing suddenly separated from the airplane. One of the witnesses stated that the other wing separated shortly after the first one. Postaccident examination confirmed that both wings were completely separated from the airplane with the exception of the right wing aft spar and aileron. Examination of the fractures in the wing attachment fittings revealed signatures consistent with overload failure with the exception of one fitting that had no perceptible damage due to deformation or fracture. The attachment bolt for the fitting that showed no perceptible overload damage was not recovered during the investigation; however, the relative lack of damage to the strut fitting indicates that the attachment bolt either failed, or its corresponding nut had loosened and separated during the flight. A portion of wing fabric retained for testing showed that the fabric met the minimum performance requirements as set forth in regulations. No preaccident defects were found with regard to the components examined.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Aircraft structural failure during enroute (cruise) defining event
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
- cause Aircraft › Aircraft structures › Fuselage › Wing attach fittings (on fus) › Failure
- cause Aircraft › Aircraft structures › Wing structure › (general) › Failure
Pilot
- Certificate: commercial pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 6,000 hours in all
- Medical certificate: Class 2 (with waivers/limitations)
- Injury: fatal
The aircraft
- Last inspection: condition inspection, August 16, 2010
- Seats: 2
- Landing gear: fixed
- Engine: Bombardier ROTAX (ALL) (piston); 0 hours total
The flight
- Departed from: 91C Prairie Du Sac WI at 7:00 pm
- Destination: RRL Merrill WI
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: scat at 3,200 ft
- Temperature: 46°F (8°C), dew point 32°F (0°C)
- Altimeter: 30.42 inHg
- Observation at 7:15 pm from DLL, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.