Pilot Debrief

MORIARTY MARVIN AVENTURA II near Minneola, FL — 2019-08-23

Final reportERA19FA256
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Date
2019-08-23
Location
Minneola, FL, USA
Airport
3FD4
Aircraft
MORIARTY MARVIN AVENTURA II
Registration
N9143M
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Takeoff roll

Probable cause

The pilot’s improper modifications to the airplane’s engine, which resulted in the partial loss of engine power. Contributing to the outcome was the pilot's exceedance of the airplane’s critical angle of attack during an attempted return to the airport following a partial loss of engine power, which resulted in an aerodynamic stall and impact with terrain.

Contributing factors

Contributing to the outcome was the pilot's exceedance of the airplane’s critical angle of attack during an attempted return to the airport following a partial loss of engine power, which resulted in an aerodynamic stall and impact with terrain.

NTSB narrative

According to the pilot's son, he and his father were working on the experimental, amateur-built airplane's carburetor the day before the accident to improve the fuel consumption. They replaced the carburetor jets with smaller ones, but that change made the engine run roughly. On the morning of the accident, the pilot told his son that he fixed the airplane by adjusting the carburetor float tabs, allowing more fuel to enter the carburetor bowl. They then performed an engine run-up, and it ran normally. The pilot’s son stated that, during takeoff, the airplane was not climbing like it had in the past. When the airplane reached about 300 ft above ground level, the engine started to sputter and run roughly. He stated that it looked like his father tried to turn the airplane back to the runway and made a sharp left turn but that shortly after the turn, the airplane descended straight down to the ground. Postaccident examination of the engine found that the choke on the carburetors was safety wired in the open position. The top spark plugs were removed and noted to be black and sooty, consistent with the engine running with an excessively rich fuel ratio. No other mechanical anomalies were noted with the engine that would have precluded normal operation. Given the available information, it is likely that the pilot’s modifications to the airplane’s engine resulted in it running excessively rich, which resulted in the partial loss of power and engine roughness that occurred during the takeoff. Additionally, the pilot exceeded the airplane’s critical angle of attack while attempting to return to the airport, which led to an aerodynamic stall and impact with terrain. Toxicological testing revealed Delta-9-THC (tetrahydrocannabinol, the active compound in marijuana) in the pilot’s blood and liver specimens; however, it could not be determined if the pilot's marijuana use impacted his behavior or decision making before or during the accident flight.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted takeoff when engine began to sputter.

NTSB coding

Evidence available

  • Photos
  • 7 docket documents
View NTSB final reportView NTSB docket

Docket documents7

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