Sonex Aircraft SONEX accident near Dowagiac, Michigan, September 10, 2023
On September 10, 2023 at about 4:00 pm local time, a 2005 Sonex Aircraft SONEX, an amateur-built aircraft,, registered N569SX, was substantially damaged in an accident during enroute near Dowagiac, Michigan (Dowagiac Municipal airport). 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 total loss of engine power due to the failure of the ignition distributor rotor.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 10, 2023 · about 4:00 pm local time
- Place
- Dowagiac, Michigan · Dowagiac Municipal · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Sonex Aircraft SONEX, built 2005, amateur-built
- Registration
- N569SX · no longer on the register · serial 0569
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot departed for a local flight and an alert notice (ALNOT) was issued when the pilot did not return. A search effort concluded four days later when the wreckage was found in a heavily wooded area about 4 miles from the departure airport. No ADS-B data associated with the airplane, or the accident flight was available. At the time of the on-scene examination, the transponder was observed in the OFF position. Impact signatures on the propeller were consistent with the propeller not rotating at impact. Examination of the engine revealed that the ignition distributor rotor was fractured and disconnected from its driveshaft. This resulted in a total loss of engine power when the ignition system became inoperative due to the rotor failure. No other preimpact mechanical malfunctions or failures were found with the airframe or engine.
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 defining event
- Off-field or emergency landing during landing
- Collision with terrain or object (not controlled flight into terrain) during landing
The NTSB's findings
- Aircraft › Aircraft power plant › Ignition system › Magneto/distributor › Failure
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 736 hours in all
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: fatal
The aircraft
- Airframe total time: 391.1 hours
- Last inspection: condition inspection, August 14, 2022
- Maximum gross weight: 1,250 lb
- Seats: 2
- Landing gear: fixed
- Engine: Corvair (piston); 47 hours total
The flight
- Departed from: C91 Dowagiac MI at 3:00 pm
- Destination: C91 Dowagiac MI
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 260° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 61°F (16°C)
- Altimeter: 30.18 inHg
- Observation at 10:53 am from KBEH, 15 miles away
Weather report (METAR): KBEH 101453Z AUTO 26005KT 10SM CLR 21/16 A3018 RMK AO2 SLP217 T02060161 53003 $
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
10 documents, released by the NTSB on August 20, 2025. 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 | Examination Summary | PDF, 6 pages · our copy | View Download |
| 2 | Maintenance Records -- Airframe | PDF, 16 pages · our copy | View Download |
| 3 | Maintenance Records - Engine | PDF, 8 pages | View Download |
| 4 | Record of Conversation - Helmholdt | PDF, 1 page · our copy | View Download |
| 5 | Investigation Photographs | PDF, 5 pages · our copy | View Download |
| 6 | Memorandum for Record A�� Airport Manager Revb | PDF, 1 page · our copy | View Download |
| 7 | Engine Test Run | video · our copy | View Download |
| 8 | Fuel Documentation | PDF, 2 pages | View Download |
| 9 | Toxicological Report | PDF, 1 page · our copy | View Download |
| 10 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 1 page · our copy | View Download |
Other NTSB records under N569SX 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.