Pilot Debrief

FLIGHT DESIGN GMBH CTLS near Fond du Lac, WI — 2016-07-28

Final reportCEN16FA290
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Date
2016-07-28
Location
Fond du Lac, WI, USA
Airport
FLD
Aircraft
FLIGHT DESIGN GMBH CTLS
Registration
N527TS
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Takeoff roll

Probable cause

Carburetor contamination following exposure to water in the fuel, which resulted in a carburetor malfunction and a partial loss of engine power. Contributing to the accident was the pilot's loss of airplane control that resulted in a stall.

Contributing factors

Contributing to the accident was the pilot's loss of airplane control that resulted in a stall.

NTSB narrative

The private pilot departed the airport in the light-sport airplane and made a left turn back toward the airport while still over airport property. The airplane was at a low altitude when it rolled to the left and impacted terrain, consistent with a loss of control following an aerodynamic stall. Witnesses stated that the engine sounded abnormal. One witness reported that the airplane did not climb above treetop height before it rolled into a steep left turn and descended into terrain. An additional witness did not see the accident occur but heard the pilot state on the radio that he was making an immediate return to the airport. The terrain in front of the pilot on departure was commercial properties and parking lots, and was unsuitable for landing. During postaccident examination, contaminants and corrosion were found in both carburetor bowls. The piston slide in the carburetor for the Nos. 2 and 4 cylinders was found stuck in the idle position in its bore on the carburetor chamber top. A white substance was present on the interior surface of the bore that prevented the piston from sliding up and down within the bore. Testing of the substance determined that it was likely contamination produced by oxidation and corrosion of the aluminum alloy carburetor chamber top because of exposure to water-contaminated fuel. The engine manufacturer had previously issued a Service Instruction (SI) that warned of the possibility of poor performance or engine stoppage due to contaminants in the carburetor float chamber. One of the sources of contaminants identified in the SI was corrosion caused by high water content in fuel. Both carburetors had been inspected in accordance with the SI about 130 flight hours and 19 months before the accident, which was within the SI recommended 200-hour inspection interval. The contaminants found in the carburetors were indicative of the use of fuel with high water content at an undetermined time, most likely after compliance with the SI.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted takeoff upon noticing engine issues.

NTSB coding

Evidence available

  • FDR / data
  • 8 docket documents
View NTSB final reportView NTSB docket

Docket documents8

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