that's a tough one.    The current Andair valve will leak because it has small holes in the "OUT" direction.   ...but it will slow things down while you are taxiing.   I would be hesitant to have a check valve with no bypass holes because the failure mode is unacceptable (internal tank pressure).
The original (Don Goetz) winglets were very small and mainly there to solve this problem.   So far, I think that is the best idea going.
(add small winglets).  It's amazing what a couple inches will do reduce spillage.

On Jun 17, 2012, at 3:49 PM, JIM HANKINS wrote:

My IVP (without winglets) leaks fuel if the ram is only slightly unlevel after refueling.  Glasair as a checkvalve-float arrangement that prevents this.
Does anyone out there have a better idea?  Low cracking pressure check valve? Anything, and any ideas accepted!  I've been using a bucket under the wingtip or leaving it unrefueled when parked.
Jim Hankins

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