Pilot Debrief

WILLIAMS JOHN TITAN T-51 MUSTANG near Geneva, OH — 2024-07-21

Final reportERA24FA310
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Date
2024-07-21
Location
Geneva, OH, USA
Airport
7D9
Aircraft
WILLIAMS JOHN TITAN T-51 MUSTANG
Registration
N751TX
Category
Airplane
Highest injury
Fatal
Fatalities
1

Probable cause

A sudden propeller overspeed and subsequent separation of the propeller blades and hub, while maneuvering at high speed and at low altitude, which resulted in a collision with a tree during the subsequent forced landing attempt.

NTSB narrative

The pilot, who was the builder of the experimental amateur-built airplane, was conducting a post-maintenance test flight. After performing several aerobatic maneuvers near the airport, the pilot began a high-speed low pass over the runway. Upon passing most of the runway, the airplane began a climb. A witness heard the engine go to a high rpm and then saw the entire propeller hub break apart. After the propeller hub fractured and separated, the airplane began a left turn toward a road. While maneuvering toward the road, the airplane’s left wing impacted a tree and the airplane subsequently rolled over and impacted terrain. Onboard recorded data revealed that, at the time the propeller separated, the engine was operating at 6,813 rpm, which equated to a propeller speed of 3,585 rpm. This speed was considerably in excess of the propeller blade blank manufacturer’s limit of 2,100 rpm. This speed would have produced a centrifugal force that was more than 3 times the design limit of the propeller blade blanks. Further examination of the onboard data revealed that, around the time of the propeller overspeed, the airplane was traveling at an airspeed about 223 miles per hour (mph); the published never-exceed speed (Vne) for the airplane was 215 mph. The data also revealed a sudden decrease in the longitudinal load factor, consistent with a sudden deceleration of the airplane, followed shortly thereafter by the longitudinal load factor returning to normal. A possible reason for the deceleration was a sudden increase in drag from the propeller blades moving to low pitch. This was followed by a reduction in drag on the airplane, which was likely due to the propeller separating from the airplane. Postaccident examination of the propeller governor, governor adapter, and the propeller gearbox revealed no evidence of any preacident mechanical failures or malfunctions that would have precluded normal operation. Ultimately, the reason for the propeller overspeed could not be determined based on available information.

NTSB coding

Evidence available

  • Video
  • Photos
  • 22 docket documents
View NTSB final reportView NTSB docket

Docket documents22

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