Amateur-built STOL CH 701 accident near Kenwood, California, July 15, 2017
On July 15, 2017 at about 6:40 pm local time, a 2010 amateur-built STOL CH 701, registered N422ES, was substantially damaged in an accident during emergency descent near Kenwood, 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).
The NTSB's probable cause their words, unchanged
Failure of the flywheel drive assembly, which resulted in a loss of engine power and subsequent forced landing to uneven terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 15, 2017 · about 6:40 pm local time
- Place
- Kenwood, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built STOL CH 701 NO SERIES, built 2010
- Registration
- N422ES · registry record · serial 7200
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that during cruise flight, a severe vibration came from the engine, and cooling fluid leaked onto the windscreen. About 30 seconds later, the engine lost total power. The pilot made a forced landing on a narrow field, and the airplane slid off the landing area into a ditch, coming to rest nose down substantially damaging the left wing and forward fuselage. An engine examination revealed that one of the spider pins and some of the material holding the pins, which connect three rubber links that transmit power between the engine and transmission, had broken. The semi-attached broken pin resulted in extreme vibration, it swung out on the other pin by centrifugal force which hit and broke the coolant line causing a loss of coolant and subsequent loss of engine power. Two days after the accident, the engine manufacturer recalled the flywheel drive assemblies and stated they would be replaced with heavier flywheel drive assemblies.
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
- Loss of engine power (total) during emergency descent defining event
- Off-field or emergency landing during emergency descent
The NTSB's findings
- Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Failure
Pilot
- Certificate: sport pilot
- Ratings: single-engine land
- Flight time: 1,900 hours in all; 1,520 in this make and model; 20 in the last 90 days; 10 in the last 30 days; 1,880 as pilot in command
- Last flight review: May 4, 2017
- Medical certificate: None
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 450 hours
- Last inspection: condition inspection, May 20, 2017; 14 hours since
- Landing gear: fixed
- Engine: Viking 110 (piston); 418 hours total
The flight
- Departed from: O60 Cloverdale CA at 6:15 pm
- Destination: 0Q9 Sonoma CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 230° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 57°F (14°C)
- Altimeter: 30.00 inHg
- Observation at 6:54 pm from KAPC, 17 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 NTSB has not released the docket for this case yet. The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), is usually released when the investigation is nearly complete, and the list here is refreshed when it appears. Check 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.