Airborne Extreme LLC SQ-12 accident near Palmer, Alaska, November 25, 2016
On November 25, 2016 at about 10:30 pm local time, a 2016 Airborne Extreme LLC SQ-12, an amateur-built aircraft,, registered N37PX, was substantially damaged in an accident during enroute (cruise) near Palmer, Alaska. It was a personal flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fuel injector manufacturer's inappropriate guidance to use a 5-ampere circuit breaker in place of the required 10-ampere circuit breaker on the fuel injector circuit, which resulted in the circuit breaker opening, a loss of electrical power to the electronic fuel injectors, and a subsequent total loss of engine power.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 25, 2016 · about 10:30 pm local time
- Place
- Palmer, Alaska · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Airborne Extreme LLC SQ-12 NO SERIES, built 2016, amateur-built
- Registration
- N37PX · registry record · serial SQ12-002
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The private pilot reported that, while in level cruise flight, the engine experienced a total loss of power; he then made a forced landing to a remote gravel bar. During the forced landing, the airplane sustained substantial damage to the left lift strut and fuselage. Following the forced landing, the pilot noticed that the 5-ampere fuel injector circuit breaker had opened. A postaccident engine run at various idle power settings revealed no evidence of any preimpact mechanical anomalies with the airplane's engine or systems. The airplane was equipped with an EFII electronic fuel injection and ignition system. A postaccident examination of the system revealed that the fuel injectors had been separated from the ignition power circuit and installed on their own dedicated circuit. The circuit was protected with one 5-ampere circuit breaker, with each individual fuel injector requiring up to 1.25 ampere of electrical current. The EFII installation manual requires one 10-ampere circuit breaker for the ignition circuit, which includes power leads for the ignition coil packs and the electronic fuel injectors. The company that installed the EFII harness provided correspondence from a previous EFII electronic fuel injection and ignition installation, where EFII had recommended that a 5-ampere circuit breaker be used if the fuel injectors were placed on their own dedicated circuit. The installation company stated that this guidance was applied to the accident airplane's installation. Because the 5-ampere circuit breaker was installed, it is likely that the circuit breaker opened and resulted in a loss of electrical power to the electronic fuel injectors, which then resulted in a total loss of engine power.
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 enroute (cruise) defining event
- Off-field or emergency landing during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine fuel and control › Fuel control electronic › Failure
- cause Personnel issues › Action/decision › Info processing/decision › Understanding/comprehension › Not specified
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 1,275 hours in all; 1,275 in this make and model; 139 in the last 90 days; 42 in the last 30 days; 1,271 as pilot in command
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: frt
- Injury: no injuries
The aircraft
- Airframe total time: 162.3 hours
- Last inspection: annual inspection, February 13, 2016; 162 hours since
- Maximum gross weight: 2,000 lb
- Seats: 3
- Landing gear: fixed
- Engine: Titan IOX-409-K7JBN (piston); 162 hours total
The flight
- Departed from: 7AK4 Wasilla AK
- Destination: 7AK4 Wasilla AK
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 120° at 3 knots
- Visibility: 10 statute miles
- Sky: overcast at 20,000 ft; a few clouds at 7,000 ft
- Temperature: 10°F (-12°C), dew point 9°F (-13°C)
- Altimeter: 29.20 inHg
- Observation at 10:53 pm from PAAQ, 30 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
7 documents, released by the NTSB on June 19, 2018. 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, 9 pages | View Download |
| 2 | Efii Installation Manual - Excerpt | PDF, 1 page | View Download |
| 3 | EFII-4R Power Wiring Diagram | PDF, 1 page | View Download |
| 4 | Email 1 - Efii Guidance to Aerotronics | PDF, 2 pages | View Download |
| 5 | Email 2 - Efii Comments | PDF, 5 pages | View Download |
| 6 | Statement of Party Representatives to NTSB Investigation | PDF, 1 page | View Download |
| 7 | Photos | PDF, 2 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.