Amateur-built 320 accident near Fond Du Lac, Wisconsin, August 8, 1996
On August 8, 1996 at about 2:02 pm local time, a amateur-built 320, registered N320L, was destroyed in an accident near Fond Du Lac, Wisconsin. 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 fatigue in the propeller flange with soft material and oversized lightening holes. A factor was the pilot's inability to maintain control of the aircraft due to the exceeded weight and balance which led to a stall/spin.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 8, 1996 · about 2:02 pm local time
- Place
- Fond Du Lac, Wisconsin · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built 320
- Registration
- N320L · no longer on the register · serial L 1987
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane experienced an inflight loss of its propeller assembly. A witness observed the airplane spiraling downward similar to that of a flat spin with smoke coming from it. Examination of the fractured propeller mounting flange revealed a separation of the propeller mounting flange from the remainder of the crankshaft which was the result of fatigue cracking that initiated between the lightening holes in the flange. There is an Airworthiness Directive and Service Bulletin that specifically addressed the subject engine when it is installed on the Piper PA-30 airplane. These inspection requirements arose because of cracking problems generated by bending of the mounting flange under certain aerobatic-type maneuvers, primarily maneuvers that add stresses from gyroscopic action. The weight and balance after the loss of the propeller was 1,531 pounds at 70.09 inches aft. The center of gravity envelope for the N320L is between 60.75 to 66.75 inches aft.
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
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; multi-engine sea; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 5,856 hours in all; 23 in this make and model; 5,666 as pilot in command; 661 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 1,502 hours
- Last inspection: 100-hour inspection, May 11, 1995; 59 hours since
- Maximum gross weight: 1,685 lb
- Seats: 2
- Landing gear: retractable
- Engine: Lycoming IO-320-B1A (piston); 0 hours total
The flight
- Departed from: OSH Oshkosh WI at 1:53 pm
- Destination: ARR Aurora IL
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 300° at 9 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 72°F (22°C), dew point 63°F (17°C)
- Altimeter: 30.00 inHg
- Observation at 1:53 pm from FLD, 4 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.