REFLECTOR: sealing the fuel tanks

[Douglas Holub]

That's right. I paint the bottom of the baggage compartment with soapy water, then I blow 1000 feet of pressure (measured with an altimeter) into the fuel tank, then watch bubbles form on the surface of the lower strakes in the baggage compartment. The fact that bubbles are coming up through the strakes tells me that the unsealed strakes are porous enough to let air through.

I could paint the baggage area strakes with Jeffco, but I don't want the fuel making its way through the foam that far. 

Doug
  ----- Original Message ----- 
  From: Alex Balic 
  To: 'Velocity Aircraft Owners and Builders list' 
  Sent: Monday, October 08, 2007 11:48 AM
  Subject: Re: REFLECTOR: sealing the fuel tanks


  Doug- I do not have a clear piture of what si happening- can you elaborate? Are the bubbles in soap film that you are applying to the baggage compartment?

   

  Alex

   


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  From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Douglas Holub
  Sent: Monday, October 08, 2007 11:06 AM
  To: reflector at tvbf.org
  Subject: REFLECTOR: sealing the fuel tanks

   

  Live and learn. I should have sealed the strakes with Jeffco in the area where the fuel tank would be, then added the bulkheads and baffles. Apparently there is a spot at the top of a fuel bulkhead where fuel tank air can get to the foam and find its way to the bottom of that bulkhead, and apparently the surface of the strake beneath that bulkhead is porous enough to let some air through, because bubbles are coming up through the surface of the strake in the baggage compartment.

   

  So now what do I do?  My fuel tank has three compartments.  One of them can be accessed via the fuel cap.  Do I cut 4" holes in the top of the other two compartments, and then brush Jeffco along the top bulkhead-strake seam, and then pull a vaccuum on the tank?

   

  Doug Holub

  Rats!



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