Davis Sonex accident near Crossville, Tennessee, February 6, 2009
On February 6, 2009 at about 9:00 pm local time, a Davis Sonex, an amateur-built aircraft,, registered N555SX, was substantially damaged in an accident during initial climb near Crossville, Tennessee (Crossville Memorial Airport). It was a flight test under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A total loss of engine power during initial climb due to the failure of the ignition power supply as a result of the improper installation of the electronic control unit.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 6, 2009 · about 9:00 pm local time
- Place
- Crossville, Tennessee · Crossville Memorial Airport · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Davis Sonex, amateur-built
- Registration
- N555SX · registry record · serial 523
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the amateur-built airplane was initiating a test flight to check a new propeller. After advancing the throttle, the airplane accelerated with normal power. However, at an altitude of 300 feet, the engine lost total power. The pilot turned back to the departure runway and landed on soft ground to the south of the runway. The landing gear collapsed, substantially damaging the firewall. Examination of the airplane revealed that continuity existed throughout the engine drivetrain, and the engine had no visible damage. The fuel was sampled and no contamination was observed. Examination of the fuel filter revealed no obstructions, the fuel pump operated normally, and the air filter was clean. The spark plugs were determined to be functional; however, no electrical energy was being delivered to the spark plugs. Further examination revealed that the electronic control unit (ECU) was not transmitting voltage to the dual coils. The ECU was manufactured to automotive specifications, and was supposed to be installed in an area of the airplane where temperatures do not exceed 65 degrees Celsius (preferably on the cabin side of the firewall). The ECU on the accident airplane was installed on the engine side of the firewall.
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
- Powerplant sys/comp malf/fail during initial climb defining event
- Loss of engine power (total) during initial climb
The NTSB's findings
- cause Aircraft › Aircraft power plant › Ignition system › Ignition power supply › Failure
- cause Personnel issues › Task performance › Maintenance › Installation › Owner/builder
Pilot
- Certificate: flight instructor, commercial pilot, military
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 5,500 hours in all; 250 in this make and model; 1 in the last 90 days; 5,500 as pilot in command; 105 on instruments
- Last flight review: February 8, 2008
- Medical certificate: Sport Pilot
- Seat: ctr
- Injury: minor injuries
The aircraft
- Airframe total time: 259 hours
- Last inspection: condition inspection, October 1, 2008
- Maximum gross weight: 1,200 lb
- Landing gear: fixed
- Engine: Ul Power 260i (piston); 0 hours total
The flight
- Departed from: CSV Crossville TN at 9:00 pm
- Destination: CSV Crossville TN
- Flight plan: none
- Runway 26, 5,100 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: from 260° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 57°F (14°C), dew point 37°F (3°C)
- Altimeter: 30.31 inHg
- Observation at 9:00 pm from CSV
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.