Navion Navion A accident near Livermore, California, December 21, 2020
On December 21, 2020 at about 11:25 pm local time, a Navion Navion A, registered N4106K, was substantially damaged in an accident during approach (VFR pattern crosswind) near Livermore, California (Livermore Muni airport). It was a flight test 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
The improper installation of the gascolator fuel inlet line and hose clamp connection, which resulted in the total loss of engine power.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 21, 2020 · about 11:25 pm local time
- Place
- Livermore, California · Livermore Muni · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Navion Navion A · all Navion As on the register
- Registration
- N4106K · registry record · serial NAV-4-1106
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane had an annual inspection and new wingtip fuel tanks installed about 6 months before the accident. The accident flight was the first flight since the maintenance. The pilot completed a normal runup inspection and the engine developed full power during takeoff. However, at an altitude of approximately 500 ft above ground level (agl), as the pilot turned onto the crosswind leg of the traffic pattern, the engine began to surge and lose power. As the pilot reduced the power for landing on the downwind leg, the engine lost total power. When the pilot realized the airplane would not make it to the runway, he prepared for a landing on the grass area parallel to the runway. The airplane touched down and the left wing impacted concrete blocks. A postaccident examination of the engine revealed a leaking gascolator fuel inlet line caused by a loose hose clamp connection on the fuel line from the fuel selector to the gascolator. The loose connection allowed a large amount of air to be introduced into the fuel line going to the engine and fuel pumps, which caused the engine to surge and eventually lose power. The examination also revealed several maintenance discrepancies. The leaking fuel inlet line was made of rubber instead of aluminum tubing, and the fuel selector's connection was improper. Additionally, the wingtip fuel tank installation revealed several inconsistencies with the installation, such as loose clamps and improper hardware installed. These discrepancies were an indication of improper recent maintenance.
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 approach (VFR pattern crosswind) defining event
The NTSB's findings
- Personnel issues › Task performance › Maintenance › Installation › Maintenance personnel
- Aircraft › Aircraft systems › Fuel system › Fuel distribution › Incorrect service/maintenance
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; multi-engine sea; single-engine land; single-engine sea; instrument: airplane
- Flight time: 17,341 hours in all; 10 in this make and model; 1 in the last 90 days; 1 in the last 30 days; 7,611 as pilot in command; 1,788 on instruments
- Last flight review: August 8, 2019
- Medical certificate: BasicMed
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 5,277 hours
- Last inspection: annual inspection, July 28, 2020; 0.2 hours since
- Maximum gross weight: 3,100 lb
- Seats: 4
- Landing gear: retractable
- Engine: Continental Motors IO-520-BB3B (piston); 69 hours total
The flight
- Flight plan: none
- Runway 25R, 5,253 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 39°F (4°C)
- Altimeter: 30.02 inHg
- Observation at 2:53 pm from KLVK
Weather report (METAR): KLVK 212253Z VRB03KT 10SM CLR 16/04 A3002 RMK AO2 SLP165 T01560039
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flig | 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 WPR21LA072.