# Accident 19960808021539A: Amtr LANCAIR320, Fond Du Lac, WI, August 8, 1996

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: August 8, 1996, 09:02 local time
- Place: Fond Du Lac, WI
- Damage: Destroyed
- Phase of flight: Normal Cruise
- Operating rules: General operating rules (Part 91)
- Location: 43.7699° N, 88.4399° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=43.7699&lon=-88.4399&mi=10
- Aircraft: N320L, a cancelled registration (https://openairdocs.org/deregistered/N320L-2013-10-25) (OpenAirDocs)
- Registry model: Neico LANCAIR 320 (registry code 05612MC, https://openairdocs.org/model/neico-lancair-320) (OpenAirDocs)
- Registry engine: Lycoming IO-320 series (registry code 41509, https://openairdocs.org/engine/lycoming-io-320-series) (OpenAirDocs)
- Reported make and model: AMTR LANCAIR320
- Reported engine: LYC IO320B1A
- People aboard: 1
- Fatal injuries: 1
- Pilot flight hours: 5,856 total, 23 in this make and model
- NTSB investigation: [NTSB CHI96FA278](https://openairdocs.org/ntsb/CHI96FA278) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19960808021539A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

(.4)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. (-23) AIRCRAFT DEPARTED OSHKOSH WISCONSIN WITTMAN AIRPORT FOR CHICAGO AREA (AURORA). WITNESSES HEARD ENGINE POPPING SOUNDS, OTHER WITNESS SAW AIRCRAFT SPIRALING DOWN TRAILING SMOKE. AIRCRAFT CRASHED IN SOYBEAN FIELD, 30 DEGRE ES NOSE DOWN, 9 DEGREES LEFT WING LOW. AIRCRAFT MISSING PROP SPINNER, PROPELLER AND STARTER RING GEAR.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CHI96FA278](https://openairdocs.org/ntsb/CHI96FA278), Aug 8, 1996: Lancair 320 (N320L), Fond Du Lac, WI, destroyed, 1 fatal. Probable cause: 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…

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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