Amateur-built STEWART S-51 accident near Jackson, California, August 5, 1998
On August 5, 1998 at about 5:20 pm local time, a amateur-built STEWART S-51, registered N151MT, was substantially damaged in an accident near Jackson, California. It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
Failure of the propeller governor pulley drive shaft due to a modification made to the system by the owner that included welding a retaining pin to the center of the heat treated drive shaft, which compromised the shaft's design strength margin.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 5, 1998 · about 5:20 pm local time
- Place
- Jackson, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built STEWART S-51 STEWART S-
- Registration
- N151MT · registry record · serial S-51D
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While en route to the destination airport, the airplane experienced a loss of engine power. The pilot made a forced landing on a highway and collided with a snow pole. The airplane veered off of the road and came to rest after it collided with a tree. The owner/builder stated that he had modified the drive shaft from the original 'V' belt drive to a dual 'serpentine' belt/pulley system. He further stated that in order to install the new belt/pulley system, he had to weld a retaining pin in the center of the original drive shaft. The propeller governor pulley was found at the bottom of the engine compartment and the shaft was found to have separated at the center point. The drive shaft exhibited a bluing and discoloration at the center where the owner had welded it on the pin. It was noted that the original manufacturer of the propeller governor drive shaft had placed a heat treat stamp on the shaft.
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
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane
- Flight time: 335 hours in all; 26 in this make and model; 49 in the last 90 days; 29 in the last 30 days; 306 as pilot in command
- Medical certificate: Class 3 (valid medical--no waivers/lim.)
- Seat: frt
The aircraft
- Airframe total time: 62 hours
- Last inspection: annual inspection; 62 hours since
- Maximum gross weight: 3,500 lb
- Seats: 2
- Landing gear: retractable
- Engine: Gm 502 (piston); 0 hours total
The flight
- Departed from: RNO Reno NV at 4:45 pm
- Destination: SBP San Luis Obispo CA
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 40 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 30°F (-1°C)
- Altimeter: 30.00 inHg
- Observation at 11:47 pm from TVL, 98 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number LAX98LA258.