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usher Fuel Cap

K

Kizad

Member
Hi!

I am having an issue with my RV9 fuel cap. I busted the pin in the fuel cap a while back and ordered a replacement cap which promptly broke when I was trying to adjust it.

These seem to be very poorly designed with major weak spots on the pin and latch. I'm looking at probably another month to get another cap ordered and am not too eager to do that considering the last one only took 5 minutes to break.

Is there another fuel cap out there that will fit the flange for the Usher fuel cap?

Much appreciated!
 
Kizad said:
Hi!

I am having an issue with my RV9 fuel cap. I busted the pin in the fuel cap a while back and ordered a replacement cap which promptly broke when I was trying to adjust it.

These seem to be very poorly designed with major weak spots on the pin and latch. I'm looking at probably another month to get another cap ordered and am not too eager to do that considering the last one only took 5 minutes to break.

Is there another fuel cap out there that will fit the flange for the Usher fuel cap?

Much appreciated!
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I am wondering about your adjustment as there are thousands of those caps being used without many complaints. Could you be adjusting it to be too tight?
 
Replacement pins should be available at any hardware store (roll pins.) I don't have the dimensions handy but from memory maybe 3/32 X 3/4"? I carry a couple spares in my flight tool kit.

There are literally a few dozen thousand of these caps in service and they are generally pretty reliable. You wouldn't be the first builder to break one or two while figuring out the right way to adjust the caps. If you give some more details on how yours broke we might be able to help.
 
Proper adjustment and proper lubrication, you won’t have any trouble with the properly designed fuel caps.

Krytox GPL 205 is the best lubricant for these fuel caps. I’ve tried many different things over the last 17 years and this is definitely worth the price. I use it sparingly once or twice a year. My RV gets flown 100+ hours per year.

The key is to get the grease completely around the large o-ring, ensuring that the grease gets in between the o-ring and the teflon contact surfaces.

Krytox grease

Looking to use Krytox on the o-rings for my usher fuel caps. There are several different types; can anyone recommend the correct type?
www.vansairforce.net
 
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I replaced the roll pin with a custom length 1/16" drill blank decades ago. The different lubes recommended above helps a lot. Fuel lube worked for me in a warm hot climate but the Krytox is the best choice for all climates especially where it gets cold.
 
RV6_flyer said:
Krytox is the best choice for all climates especially where it gets cold.
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What he said. I used Fuel Lube initially as per the instructions. Made for a hard to open fuel cap, especially when it cooled off. Krytox works great in any weather and lasts for years before needing reapplication.
 
I think the previous owner did not maintain the gas caps very well.

The original one broke trying to open the cap in cold weather.

Firstly you seem to need a tool, like your key or a screw driver to pop the latch up, which is a little annoying, but fine. My complaint isn't about that. But in the cold weather the cap is extremely tight and I was twisting the cap to try to pull it out when the pin busted.
The new one needed to be tighter to seal properly as I could still pop it out with the latch down. 83A on the diagram wouldn't turn so i tried to loosen the nut when it busted.

I know it is recommended to change the O-ring at least once a year. I am not sure how I would go about doing that if you can't loosen the nut that holds it all together.

Are you guys somehow stretching the o-ring on without disassembling the cap?

This is just very frustrating as I have been trying to get up in the air since October and it has been one thing after the other.

Hopefully I can get something as this looks to have been the last remaining Usher fuel cap available in Canada.
 
Before removing or tightening the jam nut make sure the latch is closed. This will take the pressure off the roll pin. Unscrew the washer casting (83A) and replace the O-ring or re-lube. When making adjustments for proper fitting to the tank, snug up the washer casting and then make small adjustments until it’s a good fit. The jam nut will have to be tightened and loosened each time. I CANNOT open the latch with my fingers when properly fitted. I have a plastic tool for opening the cap.

Buy one extra cap and put it in your travel tool bag. It might come in handy on the road someday.
 
Went to fly the plane today. When I was visually checking the fuel my left fuel cap pin broke. It’s been on the plane for over three years.
This is another reason to have a spare fuel cap in your tool bag. Took me a few minutes to replace and go fly.
IMG_3099.jpeg
 
Never an issue in 8 years and around 800 fillups on my 7. I would put a marker line on the bottom "washer" and found it would take 12-13 rotations to get the seal right at which point I would tighten the lock nut. Every couple years I would disassemble it and reapply a thin coating of Krytox to the orings and the top of the square washer to lube the pivot point. A little press down on the lever when you open it and the cap loosens up and comes right out with no twisting required. I found Fuel Lube made it very difficult to remove the cap but zero issues when using the Krytox 205.
 
How to get #83A loose after not being adjusted or lubed for years?

I just broke the role pin on one trying to get #83A washer to move. Ended up buying a new one. I would like to replace the #50 O-ring on the other one.
 
Foghorn said:
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A common error (warning from a friend........:rolleyes:) is, when taking the newer lids apart, to not realize that 83A is threaded! I.......I mean he actually broke the latch trying to get things to move. Learn by doing......... HOWEVER: there was a reason (of course there was)! The OLD-style caps (the ones with the BLACK "O" rings) did NOT have threaded 83 (which might be where the 83A came from: those are threaded). So: there are actually two types of this cap. The older ones have the black "O" rings, and the new replacements have the SALMON-colored "O" rings and are 'NOT ' interchangeable old to new. But one can find Viton "O" rings to replace the black ones........if you want to keep using them or have one in your tool kit as a temporary replacement.
 
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Question on fuel caps! I have a RV 3 and I have no idea of the manufacture but need to replace the gasket. There seem to be no markings. The caps do not leak and however it’s a bit difficult to put the cap back on because the rubber seals are so hour glass shaped. Any thoughts? I will update this with dimensions.
 

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J29racer said:
Question on fuel caps! I have a RV 3 and I have no idea of the manufacture but need to replace the gasket. There seem to be no markings. The caps do not leak and however it’s a bit difficult to put the cap back on because the rubber seals are so hour glass shaped. Any thoughts? I will update this with dimensions.
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Sorry, no info on the fuel cap itself. But I would seriously consider addressing the corrosion around the fuel filler neck.
 
Roadjunkie1 said:
A common error (warning from a friend........:rolleyes:) is, when taking the newer lids apart, to not realize that 83A is threaded! I.......I mean he actually broke the latch trying to get things to move. Learn by doing......... HOWEVER: there was a reason (of course there was)! The OLD-style caps (the ones with the BLACK "O" rings) did NOT have threaded 83 (which might be where the 83A came from: those are threaded). So: there are actually two types of this cap. The older ones have the black "O" rings, and the new replacements have the SALMON-colored "O" rings and are 'NOT ' interchangeable old to new. But one can find Viton "O" rings to replace the black ones........if you want to keep using them or have one in your tool kit as a temporary replacement.
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Interesting info. Last year (not knowing this), I replaced the o-rings in my old caps with the new salmon colored ones and have had no problems at all. I do use Krytox on the o-rings. I also replaced the latch assembly with new parts.
 
Kizad said:
I think the previous owner did not maintain the gas caps very well.
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The good news is that now you can maintain them!!😊
Kizad said:
The original one broke trying to open the cap in cold weather.
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Once you lift the tab, push down on it while it is 90 degrees up to help break the seal of stem and the "O" ring. If it doesn't easily move, a little penetrating oil on the stem might help (see below). If the "O" ring is stuck on the sides of the filler lid opening, a GENTLE application of a lubricant (JPL-1 or -2) might help break it loose.
Kizad said:
Firstly you seem to need a tool, like your key or a screw driver to pop the latch up, which is a little annoying, but fine. My complaint isn't about that. But in the cold weather the cap is extremely tight and I was twisting the cap to try to pull it out when the pin busted.
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If you search this on this forum you will find many handy items to help you open your fuel cap: an aluminum beer bottle opener is one. I use the screwdriver end of my fuel-sampling tube as I have it in my hand anyway having just tapped the fuel drains. Some people don't like this as the screwdriver tip is steel and can mar the lift tab on the lid. I just went out and looked at mine and they are fine after 1100+ hours.
Kizad said:
The new one needed to be tighter to seal properly as I could still pop it out with the latch down. 83A on the diagram wouldn't turn so i tried to loosen the nut when it busted.

I know it is recommended to change the O-ring at least once a year. I am not sure how I would go about doing that if you can't loosen the nut that holds it all together.

Are you guys somehow stretching the o-ring on without disassembling the cap?
Click to expand...
OK: make sure the pull tab (latch: #33 in the diagram) is DOWN before doing anything. That gives it something to push against and will save you having to replace the roll pin. The jam nut (#90) needs to be loosened and taken off FIRST before moving 83A. If 83A won't move initially, a little penetrating oil (like brand-names BLASTER or KNOCK 'ER LOOSE) will help it loosen up. I had one once that needed to be captured in the padded jaws of my vice before it decided it was coming off. :oops: Then KRYTOX lubricant on all moving/sealing parts. Expensive for a tiny tube but 🎶'a little dab'l do ya'.🎵 She'll love to run her fingers through your hair.... Oops. Sorry. Flashback there..........🤣😂

NO: the unit comes apart doing the above and one does NOT have to stretch the "O" ring around the unit which could damage it enough it would not seal. This is easy. Once you get one done, you'll likely think Oh.......that was easy......... And it is necessary maintenance so you will likely be doing it once a year or so......
Kizad said:
This is just very frustrating as I have been trying to get up in the air since October and it has been one thing after the other.

Hopefully I can get something as this looks to have been the last remaining Usher fuel cap available in Canada.
Click to expand...
If you didn't break the lift tab, replacing the roll pin is super easy and you won't need a new cap. As someone said, a proper size drill bit would be stouter.

I hope this helps get you into the air...............😊
 
Treekiwi said:
Interesting info. Last year (not knowing this), I replaced the o-rings in my old caps with the new salmon colored ones and have had no problems at all. I do use Krytox on the o-rings. I also replaced the latch assembly with new parts.
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That's why "NOT" interchangeable is in quotes in my post. I mean..........whaaaaat?
 
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