Like many of you I have battled leaking monarch’s, gotten uhh….poor customer service from Hartwig and was told over and over I am doing something wrong. Well I finally fixed the problem. In all seriousness, could never top off or the wing would spew a cloud of avgas behind it. Removed them, plated the holes. For the Cessnas with factory long range tanks, these will take care of you for way less than the $7k Textron wants for a set of caps. P/N should be 1220022-3, FYI…double check your IPC but these were pretty universal.

I'll take your caps if you are throwing them away. I have the Monarch caps on currently and have never had a problem. Having a few spares would not be a bad thing.

When I bought my 1953 180 in 2014, it came with an uninstalled set of monarch caps.
The only gripe I had with the stock caps was that the latches on the flapjack covers had broken springs.
I ended up just replacing the latches (Hartwell p/n 5000-2) on the covers, and sold off the monarchs.
Stock caps are still working great.
Every time i read one of these Monarch threads, it makes me glad I did what I did.

Stock caps FTW

S.patJ3 wrote:Like many of you I have battled leaking monarch’s, gotten uhh….poor customer service from Hartwig and was told over and over I am doing something wrong. Well I finally fixed the problem. In all seriousness, could never top off or the wing would spew a cloud of avgas behind it. Removed them, plated the holes. For the Cessnas with factory long range tanks, these will take care of you for way less than the $7k Textron wants for a set of caps. P/N should be 1220022-3, FYI…double check your IPC but these were pretty universal.

I’m certain this pic is staged for the sake of making a statement. Those are worth too much on eBay to just toss in the round file.

I was hoping to inspire a laugh or two, but in all seriousness these assemblies have had their final flight. I hope there is a definitive answer to these problems at some point. More options for these old airplanes is always a good thing.

Found this video on YouTube, identical to what this airplane was experiencing even after new seals, new vents, hours of adjusting the vents and with and without strut fairings.
https://youtu.be/XRJ4uQOM1Q8

Hello, I own a Cessna 182F in Greece with the Monarch brand caps installed for 20 years with the same o-rings. A few days ago I had a serious leak on the right wing all the way to the tail. I estimate based on the fuel gauge 30 liters. I couldn't find such o-rings with the slit here in Athens. It probably has to be a special build.
My solution: I removed the chain, straightened the chain support and installed new usual o-rings in size CS 6mm, ID 40mm (0.236, 1.5748 inch) Hardness 70
After a few flights I didn't see any leaks. However I would like to know where I can get 2 o-rings with the slit. Any information? Thanks

You can buy the o-rings from the Hartwig https://hartwigfuelcell.com/monarchcaps.php If I remember right you have to call the order in

For the record, my caps are still in a landfill somewhere (mutilated). I will not risk my conscience, sleep, A&P, IA or pilot certificates because some guy tells me these are better than an expensive night in Pattaya. They are not safe. Period (At least these particular S/N’s) and the manufacturer continually refuses to admit they have ever hear of a single problem. Cessna caps work. Not cheap, but when the engine quits because all your fuel has gone for a ride over the wing, I’d bet you would be willing to pony up twice what those caps cost to fix the problem right now.

Just sayin.

I don’t accept hack fixes in the airplanes I fly for a living, the airplanes that get my signature in the logbook, nor the airplanes that carry myself, my family or my friends; if it’s too expensive, don’t own an aircraft. While I fight rising costs every way I can, standards need to be maintained so it doesn’t begin to rain Cessnas, and further take our friends from us.

Rant over. For now.