E. D. Eliot
Well Known Member
I have a fuel cap that came with my finish kit in 2017. Do I need to drill it out or not in order to properly vent the fuel tank. Please advise. Thanks, Ed
Do not drill holes in the fuel cap.
The blue print, {Plans} of the wings should show the fuel vent line routing from the wing tanks back to the fuselage.
Originally with the RV12 classic, the fuel tank was vented with a hole drilled in the gas cap. Unfortunately this some times spit gas on the rear window and damaged it, especially the original flat cold bent lexan rear window. (The rear window was changed to molded acrylic.)
So, Van?s changed the vent system with a separate vent line. With this new vent system the fuel cap is not used to vent the tank and is therefore not drilled.
See the latest version of Section 37 - fuel tank. Can be downloaded from Vans web site.
https://www.vansaircraft.com/service-information-and-revisions/?aircraft=rv-12&doctype=all
Not sure what the RV12is does.
-Dave
Why not drill the cap too? A number of RV-12 drivers have had fuel pressure issues with a totally full tank on climb out. Theory is that fuel upon climb out blocks the new style vent. I drilled the fuel cap as a backup vent and never had that problem again.
All RV canopies will leak. That is why you always put a canopy cover on if there is any chance of rain. The standard cover extends far enough to amply cover the cap.The only downside I see to a drilled cap is water intrusion. I have been surprised to see how easily it gets in when my 12 has been on the ramp overnight in the rain during cross countries. The good news is that it seems to migrate to the gascolator rapidly and is identified during preflight the next morning. I did not expect that.
The only downside I see to a drilled cap is water intrusion. I have been surprised to see how easily it gets in when my 12 has been on the ramp overnight in the rain during cross countries. The good news is that it seems to migrate to the gascolator rapidly and is identified during preflight the next morning. I did not expect that.
If the cap is oriented in such a way that the latch cavity is angled downward so that water can easily drain out, in nearly 100 % prevents this.
Scott is your comment an endorsement for drilling a tiny hole in fuel caps to make them vented? I'm flying RV-7A and the fuel vent lines are working fine, but it does seem like a good idea to have a backup vent if a bug smacked on the vent line and plugged it.