Williams John T-51 MUSTANG accident near Oshkosh, Wisconsin, August 7, 2012
On August 7, 2012 at about 9:20 pm local time, a Williams John T-51 MUSTANG, an amateur-built aircraft,, registered N151TA, was substantially damaged in an accident during initial climb near Oshkosh, Wisconsin (Wittman Regional Airport). It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The separation of an engine cooling hose from the radiator.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 7, 2012 · about 9:20 pm local time
- Place
- Oshkosh, Wisconsin · Wittman Regional Airport · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Williams John T-51 MUSTANG, amateur-built
- Registration
- N151TA · registry record · serial M04SV6SOHK0027
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
Shortly after takeoff for a test flight, the pilot noticed that the airplane was not climbing as expected and the engine was slowly losing power. The coolant temperature was 225 degrees and the airplane was only 250 to 300 feet above ground level. During the return to the airport, the pilot heard and felt an explosion behind him and felt a burning sensation on his back. During the forced landing, the right main landing gear collapsed. Examination of the airplane revealed that a cooling line had separated from the radiator behind the pilot during the accident flight. The examination also revealed that the radiator hose line clamp for a different cooling hose was overtightened and not seated properly in its pipe bead. A replacement engine had been installed as a result of a blown head gasket during a previous flight; however, the cooling system was not replaced, and it could not be determined when the clamp was overtightened. An examination of the remaining systems revealed no anomalies.
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 maintenance event during prior to flight
- Powerplant sys/comp malf/fail during landing
- Loss of engine power (partial) during initial climb defining event
- Fire/smoke (non-impact) during landing
- Landing gear collapse during landing (flare/touchdown)
The NTSB's findings
- cause Aircraft › Aircraft systems › (general) › (general) › Failure
- Personnel issues › Task performance › Maintenance › (general) › Not specified
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 6,918 hours in all; 850 in this make and model; 6,750 as pilot in command
- Last flight review: August 12, 2011
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: frt
- Injury: serious injuries
The aircraft
- Last inspection: condition inspection, March 24, 2012
- Maximum gross weight: 1,875 lb
- Seats: 2
- Landing gear: retractable
- Engine: Honda J35A6 (piston); 0 hours total
The flight
- Departed from: KOSH Oshkosh WI at 9:15 pm
- Destination: KOSH Oshkosh WI
- Flight plan: none
- Runway 09, 6,179 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 060° at 10 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 64°F (18°C)
- Altimeter: 29.90 inHg
- Observation at 9:18 pm from KOSH, 1 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.