Results 1 to 3 of 3

Thread: Fuel system leak check

  1. #1
    Senior Member ceslaw's Avatar
    Join Date
    Sep 2013
    Location
    Carterville, IL
    Posts
    384

    Default Fuel system leak check

    Fuel Line Leak Test

    Got a question.


    The idea that a fuel leak would show up when the tanks were first filled crossed my mind as I was installing the fuel lines. Ironically, about the time I had the fuel lines in place, Mitch informed me that the manual had been supplemented with a section on this very topic. The Cubcrafter’s approach involves pressurizing the system and using soapy water to check each fitting for tell-tale bubbles.

    I pursued a bit less messy approach.


    1. The forward and aft drain lines were plugged. The aft with a radiator bleed valve, which fit perfectly; the front with a piece of 3/8” hose and a bolt.

    2. Four balloons were attached to the lines that attach to the fuel tanks. These are cheap Wal Mart party balloons which hold air for a day or so. Electrical tape assured an air tight connection.

    3. The air compressor was hooked up to the line that connects the gasolator to the fuel switch.

    Then the fun part. Pull the trigger on the air compressor and watch the balloons fill up! They were not all the same size, but they did all fill up. Then come back in 18 hours and they were still filled. So I should not have any leaks.

    DSC_0743.jpg

    I like this approach because:

    1. You don’t have to worry about over compressing the lines. A balloon will burst long before the lines will.

    2. No drippy soapy water to deal with.

    3. No chance of missing a tiny leak with said soapy water

    4. Adds a party atmosphere to a mundane work shop.

    So here is the question: Is this a reliable way to confirm the integrity of the fuel system???

  2. #2
    Member Treetopflyer's Avatar
    Join Date
    Jun 2014
    Location
    Baton Rouge, La.
    Posts
    40

    Default Re: Fuel system leak check

    I'm currently building an RV-7 (a CC is next) and the balloon test is how Vans says how to check the tanks. However, after doing the balloon test (and all appeared good) I filled my tanks with Avgas and discovered a leak. The problem with the balloon test is that the temperature in your shop will go up during the day and down at night causing the balloons to inflate and deflate a moderate amount. If you have a very small leak, the balloons may not be able to detect a leak. I even did the soap bubble test and my leak was so small that the leak didn't even show up with the bubbles. It wasn't until after I put fuel in the tank that the leak showed up. I think that both the balloon test and the soap bubble test is a good idea but if I were you I'd fill the tanks a little over half full and let them sit for a day and then flip them over and let them sit for another day and inspect the tanks for any blue stain. It's amazing how that fuel can weep out of areas that would be impossible to detect any other way. The moral to the story....I'd do all three if I were you.
    Mark

  3. #3
    Senior Member ceslaw's Avatar
    Join Date
    Sep 2013
    Location
    Carterville, IL
    Posts
    384

    Default Re: Fuel system leak check

    Now 24 hours since inflation and balloons still same size.

    while the system is pressurized I may just put some soap solution on the fittings just for peace of mind.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •