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).
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 November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 21, 2020 · about 11:25 pm local time · cases in 2020
- Place
- Livermore, California · Livermore Muni · cases near this airport · 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 other cases naming the fuel system
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 | |
|---|---|---|---|---|
| Flight crew | 1 |
Photographs from the investigation 4 pictures from the NTSB's docket, as the NTSB released them
Photo 1 – Aerial Overview of Accident Site
Photo 2 – Close-up Aerial View of Accident Site
Photo 3 – View of Left Wing
Photo 4 – View of Cinder Blocks with Red Paint TransferThe NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on August 23, 2022. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 10 pages | View Download |
| 2 | Record of Conversation FAA (NTSB) | PDF, 1 page | View Download |
| 3 | Engine Exam Report | PDF, 3 pages | View Download |
| 4 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 1 page | View Download |
| 5 | Video File | video | View Download |
| 6 | Photos FAA | PDF, 4 pages · our copy | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Connections how this case links to the rest of the register
- N4106K on the register today · the tail number may have moved to another aircraft since
- Navion NAVION A 99 registered today · the model family and its accident history
- Navion 254 aircraft on the register
- Engine: Continental Motors IO-520-BB3B 9,482 aircraft carry this series today · as the NTSB recorded it
- Livermore Municipal · nearest airport
- Accidents and incidents in California 9,080 since 1982 · 1,096 in the last ten years
- California 28,158 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/WPR21LA072.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
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 does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.