RV-6A fuel caps

Hi, I am a newbie to VAF, and yes, I have paid my dues for 2012. I have questions on the fuel caps on the flying 6A I just bought last week. One cap will bleed fuel out over night onto the wing, with full fuel. The cap does not have any material under the flipper. The other one has a flipper (I am sure that is not an RV word) that will not close down all the way and has what looks like black plastic under the lever. I have taken them apart and used fuel lube on them, but still can get the lever to fully depress on one. Any ideas would be appreciated. Thanks

TexasMatt
RV6A

Below is link to pictures of the standard Usher UD-3 fuel cap for most RVs. If that cap is your cap, you can buy the small washer for .95 and the large one for $1.95 or so. If you email Usher they will send you a reply with instructions for that fuel cap. But, basically, the nut and the plate next to the nut both are threaded and you unloosen the nut to then adjust the plate by turning it clockwise to squeeze harder or counter clockwise to squeeze the big o ring less. Fuel lube around the o ring does a good job of sealing. However, if fuel is pressurizing past the nut and up around the stud, thats what the small washer is for. Does the stuck "flipper" close when off the tank? It doesn't take much pressure on the big washer to seal properly. Chances are one or both washers need replacement if fuel lube does not help. When you open the locking lever, push it down before twisting it around, to relieve pressure. Typically, the fuel vent outlet is what will drip fuel for a pressurized tank. If you don't see fuel coming out the vent outlet under the fuselage (or wherever its been plumbed to), check for blockage of the vent line. Bees and bugs like to get in there.


http://www.aircraftspruce.com/catalog/appages/Usher_flushCaps.php

Fuel caps

Thanks very much for taking the time to explain the workings of the fuel cap, very helpful. I have two different problems with the caps. The one that leaks on the ground with expanding fuel, and slightly in flight, does not seem to squeeze the large O ring at all. I need to work on it, now that I understand how it works. The other cap's lever will not go down flush on or off the tank. There is a small black plastic (?) plate under the lever, which is not present on the other cap. It seems to inhibit the lever from going down. I will work with them, and if necessary, it may be time for new caps. I only bought the airplane a week ago and the last owner apparently lost interest in "small" items like this.

Thanks again and I am very grateful for your help.

rv-6a fuel caps

hello matt: some older rv's used a different fuel cap then newer rv's.

are both your caps the same?

i purchased a new cap for my rv years ago ,from van's,and never could get it to seal. i went back to the original cap with new parts installed.

maybe talk to someone "knowledgeable" at vans?

just my experience and this may not apply to you.

new better washers

You have the old style washers (black plastic), which have been replaced with new metal components which acually function as they should. The posts above refer you to the place for replacements. The new parts will allow easyer adjustments to fix your fuel cap ills. You dont need to replace the whole cap, just the gasket/pivot components (cheap as noted above), get them direct from the manufacturer.

From Vans Webstore:

Fuel Caps and Replacement Parts
Replacement Parts
and O-Rings


Description


Eventually you will look out on your wing just after take-off and notice that the tab on the fuel cap is sticking up because you failed to push it down. That is if you are lucky. If not so lucky, it will have rolled off the wing because you forgot to put it in the tank after refueling. Don't ask me how I know this little bit of wisdom!
The O-rings and stem seals around the fuel caps and cap center shafts don't last forever. When they wear, water may leak in with nasty results. Two styles of O-rings have been supplied in RV kits. They are not interchangeable. They are easily identified by color: older O-rings are black, newer ones are brown. The brown O-rings are generally auto fuel resistant, but their tolerance for the newer oxygenated auto fuels is unknown. The older (black) O-rings are no longer available. Upgrading to the newer O-rings requires replacing the fuel cap. New fuel caps with brown O-rings are available and fit all thereceptacles installed in the tanks.
CAUTION! If the T-406A replacement cap is to be used on the RV-12, it must be modified in accordance with the RV-12 construction manual (Section 37) to allow venting.

Ordering Information


New replacement fuel cap
CAUTION! If the T-406A replacement cap is to be used on the RV-12, it must be modified in accordance with the RV-12 construction manual (Section 37) to allow venting.
Part Number = T-406A
Price = $28.00
Quantity

Fuel cap brown O-ring
Part Number = FUEL CAP SEALS (EA)
Price = $3.00
Quantity

Fuel cap stem seals
Part Number = FUEL CAP 50
Price = $1.00
Quantity

Fuel cap stainless steel bearing washer
Part Number = FUEL CAP 40-SS
Price = $2.15
Quantity

Usher Fuel Cap Adjustment

If you go to my web site:

www.upnorthaviation.com

Select the Fuel Cap Engraving tab, scroll down and you will find the Usher UD-3 info that Usher provides to maintain and adjust your caps.

Regards,
Bill

Fuel caps

Wow, my first experience with putting a problem on the VAF site and I am blown away with the kind and helpful suggestions. I have ordered new O rings and the new lever washers from the Van's website. I also had a very fast reply to my email from Brad at Usher with regard to my problem. Thanks to Wendall, the Bills (2), Bob and Lawrence. I think I am going to like this RV stuff!

TexasMatt

Since you mentioned that your caps are not both the same, and I'm not sure if it has been made clear in the other posts... I thought I would mention that there are a number of different vintages of RV fuel caps.

They do not all adjust the same way, and the parts are not interchangeable between all of the vintages.
The earliest ones had no white delrin glide/ramp surface.
Some of the early caps adjust by turning only the nut.
Other caps use the nut as a jamb nut only, and require you to turn the disk after loosening the nut.

Fuel caps

rvbuilder2002 said:

Since you mentioned that your caps are not both the same, and I'm not sure if it has been made clear in the other posts... I thought I would mention that there are a number of different vintages of RV fuel caps.

They do not all adjust the same way, and the parts are not interchangeable between all of the vintages.
The earliest ones had no white delrin glide/ramp surface.
Some of the early caps adjust by turning only the nut.
Other caps use the nut as a jamb nut only, and require you to turn the disk after loosening the nut.

Click to expand...

Thanks for the tip. I will get a chance to take the caps apart again on Monday. They appear to be the standard caps, but one is missing the lever washer, the other one has the old style plastic washer under the lever. New parts will help when I get them next week. Appreciate the help.

Well.. Here's one more tip when you disassemble the cap..

The jamb nut may need some pressure to loosen and one of two things can happen. You can break the ears off the latch or you can snap the small pin that holds the latch on. If you snap the pin, make a new one by cutting a 3/4 inch length piece from a 1/16 drill bit. Drive out the broken pieces with a sacrificial 1/16 bit and lightly tap the replacement piece into place. Try to prevent bending the ears by squeezing them between pieces of wood in a vice while loosening the nut. Don't try grabbing onto any of the circular metal discs or they will get damaged.

Fuel caps

WenEng said:

The jamb nut may need some pressure to loosen and one of two things can happen. You can break the ears off the latch or you can snap the small pin that holds the latch on. If you snap the pin, make a new one by cutting a 3/4 inch length piece from a 1/16 drill bit. Drive out the broken pieces with a sacrificial 1/16 bit and lightly tap the replacement piece into place. Try to prevent bending the ears by squeezing them between pieces of wood in a vice while loosening the nut. Don't try grabbing onto any of the circular metal discs or they will get damaged.

Click to expand...

Thanks again Wendall. I will wait for the new parts from Van's, O rings, washers, etc. and tackle the caps this coming week.

So if I want to salvage my original fuel caps (black o rings) I will need to find them elsewhere. I did not find parts on Spruce and Van's has brown o-rings. Why not just replace the orings? What am I missing ?