Aeronca 7AC accident near Ellsworth, Nebraska, March 20, 2016
On March 20, 2016 at about 5:10 pm local time, a 1946 Aeronca 7AC, registered N84580, was destroyed in an accident during maneuvering near Ellsworth, Nebraska. It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's impairment due to carbon monoxide poisoning from a known cracked engine exhaust muffler, which resulted in a loss of aircraft control. Contributing to the accident was the pilot's decision to continue flying the airplane without properly repairing the exhaust muffler.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 20, 2016 · about 5:10 pm local time
- Place
- Ellsworth, Nebraska · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Aeronca 7AC, built 1946 · all 7ACs on the register
- Registration
- N84580 · no longer on the register · serial 7AC-3289
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The private pilot departed for a local personal flight on a winter day with an outside air temperature of about 6°C. About 1 hour after takeoff, the pilot's brother saw the airplane maneuvering near his home, which was in a rural area about 31 miles from the departure airport. The airplane did not return to the departure airport, and the accident site was located in an open field 2 days later, about 4 miles from the pilot's brother's home. Examination of the accident site revealed wreckage and impact signatures consistent with the pilot losing control of the airplane. Examination of the engine's exhaust muffler revealed cracks in several locations, and the muffler's shroud contained a layer of exhaust residue. Six months before the accident, the pilot and the mechanic who had previously performed an annual inspection on the airplane became aware of a crack in the muffler near a weld that the pilot had performed. The pilot had purchased a replacement muffler, but it was not installed before the accident. A carbon monoxide detector was not on board the airplane. Toxicology testing of the pilot's blood revealed a carbon monoxide level of 40%, which was more than enough to severely impair the pilot. The carbon monoxide likely entered the airplane's cabin because of the cracked engine exhaust muffler. The toxicology testing also revealed several non-impairing medications and two potentially impairing medications (temazepam and buspirone). According to the pilot's medical records, he was being treated for anxiety with temazepam and buspirone, and he may have been fatigued from insufficiently treated sleep disorders (insomnia and obstructive sleep apnea). However, it could not be determined whether the pilot's anxiety, the medications used to treat it, or fatigue contributed to his poor judgment in flying the airplane with known cracks in the exhaust muffler.
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 control in flight during maneuvering defining event
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine exhaust › (general) › Incorrect service/maintenance
- cause Personnel issues › Physical › Impairment/incapacitation › Carbon monoxide › Pilot
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- cause Aircraft › Aircraft power plant › Engine exhaust › (general) › Damaged/degraded
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 355 hours in all; 39 in this make and model; 5 in the last 90 days; 3 in the last 30 days; 294 as pilot in command; 0 on instruments
- Last flight review: February 26, 2016
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: frt
- Injury: fatal
The aircraft
- Airframe total time: 1,855 hours
- Last inspection: annual inspection, July 25, 2015; 7 hours since
- Maximum gross weight: 1,220 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-235-C1 (piston); 744 hours total
The flight
- Departed from: AIA Alliance NE at 4:00 pm
- Destination: AIA Alliance NE
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 43°F (6°C), dew point 10°F (-12°C)
- Altimeter: 30.22 inHg
- Observation at 4:53 pm from KAIA, 27 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
8 documents, released by the NTSB on December 11, 2017. 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 | Statement of Mechanic on Muffler Issues | PDF, 1 page | View Download |
| 2 | Photos of Accident Airplane | PDF, 6 pages | View Download |
| 3 | Toxicological Report | PDF, 2 pages | View Download |
| 4 | NTSB Medical Factual Report | PDF, 5 pages | View Download |
| 5 | Wreckage Release | PDF, 1 page | View Download |
| 6 | FAA Advisory Circular 91-59A, Inspection and Care of General Aviation Exhaust Systems | PDF, 7 pages | View Download |
| 7 | Detection and Prevention of Co - FAA Report | PDF, 111 pages | View Download |
| 8 | NTSB Safety Alert 69 - Prevent Carbon Monoxide Poisoning | PDF, 4 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Other NTSB records under N84580 the same tail number, which may have belonged to a different aircraft at the time
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.