# Accident 20240610015799A: William M Clapp CLAPP-SABERWING, Valdosta, GA, June 10, 2024

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: June 10, 2024, 20:13 local time
- Place: Valdosta, GA
- Damage: Destroyed
- Phase of flight: Cruise/Level Flight
- Operating rules: General operating rules (Part 91)
- Location: 30.7676° N, 83.3028° W: From the FAA
- Nearby events: https://openairdocs.org/map.md?lat=30.7676&lon=-83.3028&mi=10
- Aircraft: N120SW, registered now (https://openairdocs.org/aircraft/N120SW) (OpenAirDocs)
- Registry model: William M Clapp CLAPP-SABERWING (registry code 05633X7, https://openairdocs.org/model/william-m-clapp-clapp-saberwing) (OpenAirDocs)
- Registry engine: Amateur-built UNKNOWN ENG (registry code 99999, https://openairdocs.org/engine/amateur-built-unknown-eng) (OpenAirDocs)
- Reported make and model: WILLIAM M CLAPP CLAPP-SABERWING
- Reported engine: CORVAIR 100HP
- People aboard: 1
- Fatal injuries: 0
- Other injuries: 1
- Pilot certificates: Commercial pilot
- Pilot flight hours: 2,166 total, 436 in this make and model, 18 in the last 90 days
- NTSB investigation: [NTSB ERA24LA258](https://openairdocs.org/ntsb/ERA24LA258) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/20240610015799A

## Narrative

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

THE VALDOSTA REGIONAL AIRPORT AIR TRAFFIC CONTROL TOWER RECEIVED AN EMERGENCY DECLARATION DUE TO AN ENGINE FAILURE.  PILOT REPORTED ENGINE FAILURE EIGHT MILES SOUTHWEST OF VLD AND SUBSEQUENTLY PERFORMED AN EMERGENCY LANDING IN A FARM FIELD, TWO MILES SOUTHWEST OF VLD.  UPON FINAL APPROACH TO THE EMERGENCY LANDING FIELD, THE AIRCRAFT STRUCK A POWERLINE.  INSPECTION AT THE ACCIDENT SITE REVEALED THE POWER LINE WAS WRAPPED AROUND THE LEFT MAIN LANDING GEAR, PULLED THROUGH THE LEFT WING, CUT THROUGH THE RIGHT WING, AND ALSO WRAPPED AROUND AND PULLED THROUGH THE EMPENNAGE, RENDERING THE VERTICAL AND HORIZONTAL CONTROLS UNUSABLE.  THE AIRCRAFT IMPACTED THE GROUND AND CAME TO REST INVERTED, FACING 180 DEGREES FROM THE DIRECTION OF TRAVEL.  CONTINUITY OF FLIGHT CONTROLS COULD NOT BE DETERMINED, DUE TO HEAVY DAMAGE FROM THE POWERLINE, SEPARATED HORIZONTAL STAB, AND THE SEPARATED RIGHT WING AND AILERON.  FUEL WAS OBSERVED DRIPPING FROM THE LEFT WING FUEL TANK AND CENTER FUEL TANK; QUANTITY COULD NOT BE DETERMINED DUE TO AIRCRAFT BEING INVERTED.  NEITHER THE PROPELLER OR NOSE CONE SHOWED EVIDENCE OF THE AIRCRAFT MAKING POWER AT THE TIME OF THE ACCIDENT.

PILOT STATED THAT DURING THE FLIGHT, HE WAS ELECTRICALLY SWITCHING THE IGNITION SYSTEM FROM ONE DISTRIBUTOR TO THE OTHER TO NOTE DIFFERENCES IN PERFORMANCE.  IT WAS AT THAT TIME THAT HE EXPERIENCED THE ENGINE FAILURE.

POST ACCIDENT INVESTIGATION REVEALED THE CAM GEAR KEY WAY WAS SHEARED AND THE GEAR HAD SLIPPED ROTATIONALLY ON THE CRANKSHAFT APPROXIMATELY THIRTY DEGREES OUT OF PROPER TIMING.  IT IS BELIEVED THAT THE SHOCK OF SWITCHING BETWEEN THE IGNITION SYSTEMS MAY HAVE BEEN THE CAUSE OF THE SHEARED KEY.

KNOWN DAMAGE INCLUDES BROKEN MAIN LEFT LANDING GEAR, SEPARATED RIGHT MAIN LANDING GEAR, TWO OF THE THREE PROPELLER BLADES BROKEN, SMASHED NOSE CONE, BROKEN ENGINE MOUNTS, COWLING HEAVILY DAMAGED, DAMAGED COCKPIT HATCH, FUSELAGE BROKEN IN HALF AFT OF COCKPIT, RIGHT WING SEPARATED FROM FUSELAGE AND BROKEN, LEFT WING HEAVILY DAMAGED, VERTICAL STABILIZER DAMAGED, AND HORIZONTAL STABILIZER TORN FROM EMPENNAGE.

NOTE: THIS ACCIDENT IS STILL UNDER INVESTIGATION BY THE FAA AND NTSB, AND THIS REPORT MAY BE AMENDED WHEN MORE INFORMATION BECOMES AVAILABLE.

## 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 ERA24LA258](https://openairdocs.org/ntsb/ERA24LA258), Jun 11, 2024: Clapp Saberwing (N120SW), Valdosta, GA, substantial damage. Probable cause: The total loss of engine power due to the shearing of the woodruff key that indexed the crankshaft gear and hub assembly to the crankshaft, which resulted in the gear and hub rotating from their…

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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