REFLECTOR: Auto fuel - composite compatibility

John Tvedte JohnT at comp-sol.com
Mon Jul 31 13:33:53 CDT 2006


Al,
 
I think I'd drain the fuel pronto.  On the Canard aviators forum - they were just talking about ethanol in the fuel (Not marked as such) - around 7+%.  Also what additive packages are being used - as you know - is ??
 
I think I'd then fix the pin hole leaks - and as hard as this may seem  - slow down a touch - until you make darn sure you are happy with moving forward.
 
I've read too many posts, and have enjoyed so many pictures of your project over the years - I don't want to read anything happening....
 
John

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Al Gietzen
Sent: Monday, July 31, 2006 12:25 PM
To: reflector
Subject: REFLECTOR: Auto fuel - composite compatibility



For those using, or plan the use of mogas.  I'm suspecting some fuel compatibility issues.

 

I first put fuel in the tanks nearly 2 years ago and used Chevron regular. Everything was fine.  When I moved the plane to the airport 3 months ago (tanks empty) I filled with Exxon-Mobile.  Four troubling things have come up in the past few weeks. 

 

1.	I have Vance Atkinson site gauge that has a white plastic back plate for easier reading of the fuel level. The small hole through the backing has been swelling shut so the sight gauge no longer works. I contacted Vance who said that there are hundreds of these gauges in EZs using mogas without problems, but he has had 3 incidents like mine in the last three months. 
2.	A couple of weeks ago there was suddenly a pinhole leak in one of the gear well enclosures.  These enclosures are part of the fuel tank wall, and are parts that come with the Velocity kit.  These are also made and coated with EZ-poxy. 
3.	Looking in through the filler cap I see reddish-purple splotches and streaks on those gear leg enclosures.  Poking and scratching with some safety wire on a stick does not indicate any softness of the surface.  All other surfaces look fine. 
4.	Yesterday, under the leading edges of one of the strakes, I noted an area with some slight surface irregularity.  Pushing on it suggests some sponginess.  This is ½" foam core material, and indicates the possibility of a pinhole leak in the inner skin, and fuel softening the PVC foam.  PVC foam is supposed to be unaffected by fuel. 

 

My tanks (strakes) were made and coated with EZ-poxy back in 1998.  At the time I polled EZ flyers about their experience, and talked to reps of various epoxy manufacturers about auto fuel compatibility.  All the evidence said go with the EZ-poxy (see my posting of July, 1998). 

 

I realize that his may be only my issue and not related to brand; but - - Any others having any trouble with auto fuel?  Anybody using Exxon-mobile fuel?  Know of any new additives that may be an issue?

 

I'm thinking I should drain this fuel ASAP, but then what?  Other brand?  That expensive Avgas?  Regardless I may be faced with cutting open a strake at some point, but right now we are trying to get first flight done this coming weekend.

 

Al

 

 

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