The 912uls engine on my airplane has a fuel return line to the tank from the 4 way cross split. In other words line from fuel pump. line to carb 1, line to carb 2, line to tank. Other than to prevent vapor lock is this return to tank line absolutely necessary? Can this line be eliminated on an experimental aircraft?

  • Re: Fuel Return Line to tank

    by » one month ago

    In the standard Rotax 912 installation is a return fuel line, that branches off the line between the fuel pump and the carbs. Via this return line surplus fuel flows from the fuel pump back to the tank. Most cars with carbs have a similar installation.
    This return line serves to avoid the formation of vapour locks.

    As per the ROTAX installation manual, a Mandatory “restricted” fuel return line is to be incorporated within the aircraft's fuel system. The purpose of the fuel return line is to help bleed off any vapors that may form within the fuel system that could cause vapor lock, resulting in a possible loss of engine power.

    Please reference the latest ROTAX installation manual and check with the manufacturer of the aircraft to verify that a fuel return line has been incorporated within the design of the aircraft's fuel system.

    one of design is shown in picture.

    26443_2_fuel system.GIF (You do not have access to download this file.)
    26443_2_Fuel diagram.png (You do not have access to download this file.)

  • Re: Fuel Return Line to tank

    by » one month ago

     Have a read through this safety article (Which xìng wang quoted from above)

    Thank you said by: 姓, xìng wang

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