During annual.

[JAG]

bking,
Those valves are easy to replace - just pop the wing tip off and it is right there. I have never taken it apart before on the C337, but if it is like other ones I have, it is a basically a small flapper valve in side with a light spring. Not very prone to failure except the spring may break. I might suggest taking the wing tip off and verifying that the arrow on the check valve is pointing the right direction (toward the tanks). If it is installed correctly, remove it and check it by blowing into it. It should free flow the one way and restrict the other. Still problems, next thing I would try is soaking it in in Varsol/Mineral Spirits) to clean it. Try cleaning and flushing it before opening it up. If you still can't get it to work properly, then open it up.. Basically one end screws off, and it seals with an aluminum washer. You can reuse the washer (may need a light dressing to smooth it out before reinstallation). Once you have the end off, you will clearly see the flapper and spring I am talking about. Hopefully, it is just some garbage (bugs or something) under the flapper. Just be careful not to damage the flapper and spring, it is really light duty to function properly. Let us know what you find!
Jeff

[bking]

JAG,

I removed the check valve yesterday afternoon and found the flow was correct and that it was clean, but would not hold back pressure. To test the valve, I covered the weep holes, blew through it and it leaked so I dissembled it and found the neoprene seal on the disc was cracked in several places. Yuengling has them in stock so I placed an order for 2 new valves and expect them tomorrow.

Thank you for the help.

[JAG]

bking - thanks for the feedback and the report on the deterioration on the check valve. Likely there a few more Skymasters out there with similar or soon-to-be problem like that. Appreciate the follow up.

Regards,
Jeff

[mshac]

Originally Posted by bking

neoprene seal on the disc was cracked in several places. Yuengling has them in stock

For future reference, would you mind posting the part number, and the price too if possible? Someone is thanking you in the future...

[bking]

The revised Cessna part number for the vent check valve is S2358-1 purchased through Yingling @ $278.30 each.

[Multimotor]

Originally Posted by bking

The revised Cessna part number for the vent check valve is S2358-1 purchased through Yingling @ $278.30 each.

$248.48 directly from Cessna, as opposed to cessnadirect dot com, which is Yingling.

https://ww2.txtav.com/Parts/PartSear...Detail/S2358-1

Seeing prices requires an account and a login. Everyone should have an account anyway, so things like the parts manual and service bulletins are accessible.

Free shipping over $250, if the order is placed online.

[YankeeClipper]

My IA damn near stripped it to the steel for the first annual (which is still not finished). He is as risk averse as your local FSDO, but I sincerely appreciate it. Having said this, my plane sat for literally 10 years in the hanger when I bought it, and had very few hours for many years prior to that. If my plane had a full year of flying in 21, and it had an annual back then without any significant caveats in the notes, I don't think my IA would have removed the tips either. There are only so many cycles of tighten and loosen available to all of that hardware.