CHI96FA278 · Lancair 320
Lancair 320 · Accident: propeller failure/malfunction en route
From Wittman Regional Airport (OSH) to Aurora Municipal Airport (ARR)
Event
- NTSB case
- CHI96FA278
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 1 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Lancair 320
- Aircraft type
- Lancair 320
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N320L
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Wittman Regional Airport (OSH), Oshkosh, WITo Aurora Municipal Airport (ARR), Aurora, IL
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Propeller failure/malfunction
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Stall/spin
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Engine assembly, crankshaft › Fatigue
- Pilot in command › Aircraft control, not possible
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
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 which led to a stall/spin.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI96FA278
- Event ID
- 20001208X06424
- Case number
- CHI96FA278
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 2060189c359ef11d71a7582175b76a0cd867d060e5fd8eeb6ee0c5dfa2b2e364; retrieved 2026-09-20T23:14:13.298Z.