Pilot Debrief

FK LIGHTPLANES FK9 ELA SW near Canton, GA — 2014-01-04

Final reportERA14LA089
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Date
2014-01-04
Location
Canton, GA, USA
Airport
CNI
Aircraft
FK LIGHTPLANES FK9 ELA SW
Registration
N611SP
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

A partial loss of engine power during cruise flight due to an overly lean fuel-air mixture, which resulted from an incorrectly installed float chamber vent line and led to a subsequent off-airport landing.

NTSB narrative

The pilot reported that, while in cruise flight, the engine experienced a partial power loss. The airplane was unable to maintain altitude, so the pilot chose to perform an off-airport landing to an open field. During the landing roll, the airplane encountered a berm, became airborne, and then landed hard. Examination of the engine revealed that the carburetor float chamber vent lines had been incorrectly routed to the air filter. The engine manufacturer's installation manual cautioned that the float chamber vent lines must not be routed into the slipstream or down the firewall because "pressure differences between the intake pressure in the carburetor chambers may lead to engine malfunction due to incorrect fuel supply." Therefore, it is likely that the incorrectly installed vent line resulted in back pressure to the float bowl that exceeded the normal operating range, which would have affected the engine's fuel-air mixture and led to the partial loss of engine power.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have checked fuel levels before flight to prevent power loss.

NTSB coding

Evidence available

  • FDR / data
  • Photos
  • 14 docket documents
View NTSB final reportView NTSB docket

Docket documents14

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