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Thread: Fuel flow test procedure

  1. #1
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    Default Fuel flow test procedure

    I can't seem to find the fuel flow test procedure for the CC340. Wondering if someone can point me in that direction. Thanks, Tom

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    Default Re: Fuel flow test procedure

    Quote Originally Posted by Tom R View Post
    I can't seem to find the fuel flow test procedure for the CC340. Wondering if someone can point me in that direction. Thanks, Tom
    Tom,

    what i I did was mark a 5 gallon gas can with marks for each gallon. Pour a measured amount into the left fuel tank (like 3 gallons) and be sure the fuel selector is off. Check for any fuel leaks in the wing or fuselage or fuel selector area.

    Remove the fuel line where it goes into the carb and place it into the empty, marked fuel can. (I put the fuel can on a small table so the short hose would reach).

    Turn on your stopwatch on your iPhone and have it ready to start. Turn the fuel selector to the left tank and then watch for the fuel to start coming out of the hose and into the fuel can and start the stopwatch when it does.

    Note the time it takes to fill to fill to each gallon mark on the fuel can.

    You need to see about 18 gph of fuel flow which is 150% of max fuel burn in full power climb. So you should flow a gallon in 3.33 minutes or less.

    Do do the same for the right tank. It wil flow different from the left tank due to the routing of the fuel lines. Also note that the actual fuel flow rates will be greater when flying because the forward facing fuel vents takes in ram air and further pressurized the fuel tanks.

    Also, if you have a fuel flow meter att here's after the gasolator that it may flow very slow to start (or not at all) due to the fuel flow metering device being froze up with the factory lubricating grease. Just leave the fuel selector on and let it sit for awhile and it will eventually loosen up and spin, allowing the fuel to flow. When it's flowing good, then just shut off the fuel selector, drain the fuel can and start to measure again.

    Hope me that helps.

  3. #3
    Member DRL's Avatar
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    Default Re: Fuel flow test procedure

    Quote Originally Posted by Tom R View Post
    I can't seem to find the fuel flow test procedure for the CC340. Wondering if someone can point me in that direction. Thanks, Tom
    Not sure why you need to do that. One of the benefits of building the finest kit available is that most of the engineering has been done for you. Just so long as nothing has been modified and there are no building errors, you should be okay. The design has been around a very long time and gravity has never been known to fail. Nevertheless, doubt is an issue until the first takeoff, and then, it just seems to disappear.

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    Default Re: Fuel flow test procedure

    Quote Originally Posted by DRL View Post
    Not sure why you need to do that. One of the benefits of building the finest kit available is that most of the engineering has been done for you. Just so long as nothing has been modified and there are no building errors, you should be okay. The design has been around a very long time and gravity has never been known to fail. Nevertheless, doubt is an issue until the first takeoff, and then, it just seems to disappear.
    For certain it is well engineered and fuel flow is well over
    minimim requirement......but.....

    - what if something was in the fuel line and obstructs fuel flow?
    - what if a connection wasn't secure

    Also, you are required to do the fuel flow test, with results posted and sign that you did in order to receive your Special Airworthiness Cert. This of course is for the EX build/certification.
    Last edited by Daveembry; 07-26-2017 at 06:38 AM.

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    Member DRL's Avatar
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    Default Re: Fuel flow test procedure

    Quote Originally Posted by Daveembry View Post
    For certain it is well engineered and fuel flow is well over
    minimim requirement......but.....

    - what if something was in the fuel line and obstructs fuel flow?
    - what if a connection wasn't secure

    Also, you are required to do the fuel flow test, with results posted and sign that you did in order to receive your Special Airworthiness Cert. This of course is for the EX build/certification.
    It certainly can't hurt, it just takes time. We must have missed that requirement, it was not in our build manual, but those have changed quite a bit since we finished #16. It would seem to have been complied with when the kit was approved, but Mitch would know for sure. No doubt, if someone deviates from the design they have the requirement.

    We did run air through the lines and vacuumed the tanks as suggested. The worse case would be something getting loose after assembly that blocks a line. So far, during our condition inspections we haven't seen any debris in the gascolator. Of some concern though, is water getting into the system from an external source, or someone putting the caps on backwards. An improvement would be a cap that would install in only one position. We try to fuel it ourselves.

    We were fortunate, the only leak we found was at the rear drain, very little fuel makes a very big mess. In any case, it is probably a good idea to leak check before the side panels go on.

    Good luck with your build.

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