Amateur-built STEEN SKYBOLT accident near Sonora, California, August 31, 1986
On August 31, 1986 at about 4:50 pm local time, a amateur-built STEEN SKYBOLT, registered N69Z, was substantially damaged in an accident near Sonora, California (Sonora airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries; 1 other was unhurt. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The NTSB has not yet published a probable cause for this accident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 31, 1986 · about 4:50 pm local time
- Place
- Sonora, California · Sonora · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 1 other was unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built STEEN SKYBOLT STEEN SKYB
- Registration
- N69Z · registry record · serial 200-2
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
AN AMATEUR BUILT PHILLIPS STEEN SKYBOLT EXPERIENCED AN INFLIGHT FAILURE OF THE UPPER WING PANEL FABRIC WHICH LED TO A RAPID DESCENT AND SUBSEQUENT HARD LANDING IN A PARKING LOT. EXAMINATION OF THE WING PANEL REVEALED NO EVIDENCE OF GLUE OR BONDING MATERIAL HAVING EVER BEEN APPLIED TO THE FABRIC TO SECURE IT TO THE CENTER SECTION.
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: 590 hours in all; 104 in this make and model; 15 in the last 90 days; 15 in the last 30 days; 547 as pilot in command; 43 on instruments
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: rear
The aircraft
- Airframe total time: 186 hours
- Last inspection: 100-hour inspection, July 22, 1986; 8 hours since
- Maximum gross weight: 2,150 lb
- Seats: 2
- Landing gear: fixed
- Engine: Continental I0-470 SERIES (piston); 0 hours total
The flight
- Departed from: 022 Sonora CA at 4:30 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 30 statute miles
- Sky: clear
- Temperature: 0°F (-18°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.
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 LAX86FVG07.