Bede Corp BD-4 accident near Lowell, Indiana, November 14, 2023
On November 14, 2023 at about 7:53 pm local time, a 2015 Bede Corp BD-4, an amateur-built aircraft,, registered N931AS, was substantially damaged in an accident during enroute (cruise) near Lowell, Indiana. It was a personal flight 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
Fatigue cracking of the propeller blade root, which resulted in the in-flight separation of the propeller blade from its root. Contributing to the accident was the improper machining of the blade root threads, which resulted in chatter/ratchet marks that weakened the strength of the blade root.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 14, 2023 · about 7:53 pm local time
- Place
- Lowell, Indiana · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bede Corp BD-4 C, built 2015, amateur-built
- Registration
- N931AS · registry record · serial 1359B
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
About 25 minutes after takeoff, the engine started to run rough and shake violently. The pilot performed an off-airport landing in a soybean field. Upon touchdown, the airplane flipped inverted, which resulted in substantial damage to the fuselage. When the pilot exited the airplane, he discovered one of the propeller blades was missing. The pilot had installed the propeller about 18 months before the accident but had to replace the blades after 12 hours of service because the propeller blades were backing out of the hub. The manufacturer sent the pilot three new blades, which contained retention pins. Metallurgical examination of the blade root of the missing propeller blade revealed multiple fatigue cracks that initiated at the inner surface of the blade root where thread roots intersected a radial hole for the retention pin; the radial hole for the retention pin was located where the composite section of the propeller blade integrated with the metallic root. The darker appearance of the thumbnail-shaped region and curved bands of progression marks emanating from the cracks suggest they had initiated and had been growing before the accident flight. Chatter and ratchet marks, most likely a result of machining, were seen on the threads of the retention pin holes. A cross-section examination of the remaining two propeller blade roots revealed similar fatigue cracks emanating from the retention pin holes. The cracks were not visible from the surface and therefore would not be seen during routine propeller inspections. It is likely that the combination of the chatter/ratchet marks and operational vibrations resulted in fatigue cracking and ultimately overstress failure, which caused one of the propeller blades to separate at the blade root.
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 enroute (cruise)
- Part(s) separation from AC during enroute (cruise) defining event
- Off-field or emergency landing during landing
- Roll over during landing
The NTSB's findings
- Aircraft › Aircraft propeller/rotor › Propeller system › Propeller blade section › Failure
- Aircraft › Aircraft propeller/rotor › Propeller system › Propeller blade section › Fatigue/wear/corrosion
- Personnel issues › Task performance › Maintenance › Fabrication › Owner/builder
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 408 hours in all; 200 in this make and model; 32 in the last 90 days; 15 in the last 30 days; 293 as pilot in command
- Last flight review: August 15, 2022
- Medical certificate: BasicMed (with waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Airframe total time: 234 hours
- Last inspection: condition inspection, July 1, 2023
- Maximum gross weight: 2,500 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-360-A1A (piston); 3,243 hours total
The flight
- Departed from: KIGQ Lansing IL at 7:30 pm
- Destination: 5011 Bainbridge IN
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 170° at 10 knots, gusting 14
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 23°F (-5°C)
- Altimeter: 30.32 inHg
- Observation at 1:55 pm from KRZL, 14 miles away
Weather report (METAR): KRZL 141955Z AUTO 17010G14KT 10SM CLR 16/M05 A3032 RMK AO2
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on April 23, 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 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 11 pages | View Download |
| 2 | Maintenance Records | PDF, 1 page | View Download |
| 3 | Photos | PDF, 3 pages | View Download |
| 4 | Excerpt from Operator's Manual | PDF, 1 page | View Download |
| 5 | Memorandum for Record A��pilot | PDF, 1 page | View Download |
| 6 | Materials Laboratory Factual Report 24-063 (CEN24LA038) | PDF, 18 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 N931AS the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CEN24LA038.