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  #1  
Old 01-12-2022, 11:13 AM
MarkCFI MarkCFI is offline
 
Join Date: Apr 2020
Location: Upstate NY
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Default Fuel Cap O-Rings

I noticed some venting through one of my caps. I ordered both the large and small O-rings.

However the bottom plate on my cap does not turn to tighten. Its basically loose on the shaft. Itís not threaded and it appears the only way to tighten is via tightening the lock nut on the bottom.

Iím assuming thatís the way to tighten but thought so would ask before I head back up to the airport with the new O-rings.
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  #2  
Old 01-12-2022, 11:40 AM
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FORANE FORANE is offline
 
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Usher UD-3 fuel caps
The bottom plate is threaded and is used to set o-ring tension.
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  #3  
Old 01-12-2022, 12:23 PM
MarkCFI MarkCFI is offline
 
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Location: Upstate NY
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Thanks

Thatís the diagram I referred to when ordering the o-rings. However when I removed the locknut on the bottom the lower washer plate just comes off. It does not seem to be threaded.

Incidentally the cap on the left wing looks like the diagram but the right wing is slightly different. The lower washer plate is ďthinnerĒ on the right wing

Im thinking I might have a different cap on the right wing.

The o-ring is damaged and has a nick but it seems to be the same as I received.

Iíll head back to the airport and pull the cap completely apart and see what I have.

Thanks again
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  #4  
Old 01-12-2022, 02:15 PM
pa38112 pa38112 is offline
 
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If I recall correctly, my caps just have the nyloc nut on the bottom. Put on the new O-rings and tighten them a little at a time until the cap wont turn in the fuel neck when the locking tab is down. They should remove freely when the tab is up. If you tighten too much, you will knw, because it will require some wiggling to remove the cap with the locking tab up.
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  #5  
Old 01-12-2022, 03:18 PM
MarkCFI MarkCFI is offline
 
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Thanks

I think thatís the way the cap in the right wing works. The one in the left wing is different and looks like the picture posted earlier. Iíll go up and put the new o ring on but I suspect I will buy a new cap just so they match.

I appreciate the comments
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  #6  
Old 01-12-2022, 10:52 PM
PCHunt PCHunt is offline
 
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IIRC, the older Usher caps just had a Nyloc nut to adjust the amount of closure. The newer ones have a second threaded fitting so you can tighten them together after adjusting, for a more secure lock.

Or something like that.........
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  #7  
Old 01-13-2022, 05:53 PM
MarkCFI MarkCFI is offline
 
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Replaced both large and small gasket on the cap in question, test flew with no leaks or venting. Might adjust the tightness a bit but so far so good.

I appreciate the help

V/R
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