Amateur-built RV4 accident near Napa, California, August 5, 1991
On August 5, 1991 at about 3:20 am local time, a amateur-built RV4, registered N835B, was substantially damaged in an accident near Napa, California. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE INSTALLATION OF A NON COMPATIABLE OIL FILTER AND SYSTEM PLUMBING CHANGES WHICH INDUCED THE OIL EXHAUSTION EVENT RESULTING IN A FORCED LANDING AND IN FLIGHT COLLISION WITH TERRAIN.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 5, 1991 · about 3:20 am local time
- Place
- Napa, California · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built RV4
- Registration
- N835B · registry record · serial 1171
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PILOT SAID THE AIRCRAFT WAS IN CRUISE FLIGHT WHEN THE OIL PRESSURE SUDDENLY DROPPED. THE ENGINE BEGAN TO RUN ROUGH, THEN SEIZED ALTOGETHER. THE AIRCRAFT WAS CLOSE TO A PRIVATE AIRSTRIP AND THE PILOT WAS ATTEMPTING A FORCED LANDING ON THE AIRSTRIP. THE AIRCRAFT LANDED SHORT OF THE RUNWAY IN A GRAPE VINEYARD. RESPONDING SHERIFF'S DEPUTIES REPORTED THAT THE ENTIRE BELLY OF THE AIRCRAFT WAS HEAVILY COATED WITH OIL. FAA AIRWORTHINESS INSPECTORS EXAMINED THE AIRCRAFT AND FOUND THAT AN AUTOMOTIVE FRAM OIL FILTER WAS INSTALLED ON THE ENGINE, WITH SOME PLUMBING CHANGES. THE INSPECTOR STATED THAT THE OIL FILTER FAILED TO BYPASS OIL. THE OUTSIDE CASE OF THE FILTER WAS FOUND TO HAVE EXPANDED TO ABOUT 125 PERCENT OF NORMAL SIZE AND WAS LEAKING OIL.
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
- Flight time: 1,541 hours in all; 100 in this make and model; 40 in the last 90 days; 21 in the last 30 days; 1,400 as pilot in command
- Medical certificate: Class 3 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Last inspection: inspection type not recorded; 0 hours since
- Maximum gross weight: 1,550 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-320-B3B (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: dusk
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.