REFLECTOR: Leak testing Fuel Strake

[Joe Ewen]

Larry,
I would be concerned putting even 2 to 3 pisg into the strake.  When I tested my strakes, I connected a balloon to the fuel side plumbing and a hose to the vent line.  The fuel cap will not be airtight, I sealed the caps with a wide making tape (wide enough to completely cover the cap without any seams.  multiple layers of masking tape will allow a pin hole and make it look like you have a leak.)  I then blew into the vent line until the balloon was inflated to the desired level.  I did this in the early afternoon and was concerned near nightfall when the balloon was shriveled, but I did some calculations using the Ideal Gas Law and found that the temperature change was sufficient to deflate the balloon.  I waited until the next day when the temp was approximately the same as when the test was started and sure enough the balloon was back to its inflated state.  Later in the day when the temp was +10 to 15 F over when I started the test the balloon burst.  At this point I was satisfied that my tanks were leak free (hopefully they will stay that way when they undergo the dynamic stresses of flight.)

Whether you use a balloon, manometer, altimeter, etc.  remember the pressure will change with change in temperature under a constant volume (Ideal Gas Law), so don't jump to the conclusion of a leak if your pressure drops when the temperature drops.  I will recheck my tanks before I add fuel, but this time I will pot a thermocouple into the tank to monitor the gas temperature and the tank pressure sensor (I built a sensor array to monitor tank pressure in flight so if I were to have a vent problem in flight, I will know before the fuel pumps start to starve.)

Joe



  ----- Original Message ----- 
  From: Milehitaz at aol.com 
  To: reflector at tvbf.org 
  Sent: Friday, April 06, 2007 2:04 AM
  Subject: Re: REFLECTOR: Leak testing Fuel Strake


    
  Forgive me wise collective:

  I know I have read several of the posts before, never paid enough attention to the answers as it always seemed like it would be so long before I needed the info...

  Other than refrigerant and a "sniffer" to test the "seal" on my strakes...Does someone have a good method they can share? My thought was low air pressure, 2 to 3 psi  and a water bottle with a little soap in it ....spray around the outside of the strake... see if I can blow some bubbles...Thanks in advance for your input,
  Larry Lambert XL/RG






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