During annual.
 

During annual for a new shop that has never worked on a 337, is it normal practice to not remove wing tips and wing root covers?

I don't think those would normally be removed during an annual, unless there was an AD that required it for some reason, i.e. to inspect wing bolts or similar. Beechcraft has an AD to that effect on some models.

Panels removed
 

I am not sure what's normal, but I can tell you that I remove the wing root panels. This allows me to inspect wing attach points, fuel selector valves (visual and lubricate) and general visual of wiring, cables and fuel lines for any issues.

I don't normally remove the wing tips - as I can inspect function of the fuel vent valves on my A model without removing. That is about the only thing under my wingtips that are worth looking at. That being said, I remove them every second annual so I can have a good visual look around for any mud daubers.

Jeff

While certainly a good thorough annual inspection could go much farther, the "FAA Minimums" for an annual inspection don't require removal of either item. As was mentioned, there are other excellent reasons to remove them, but your shop may charge you extra because it isn't in the FAA requirements.

What are the FAA requirements? Well here they are: https://www.cessnaflyer.org/knowledg...checklist.html

Part 43 Appendix D, subsection F says you SHALL inspect wing attachment; therefore, removal of the wing to body fairings (and cuffs on struts) would be required to inspect - or have I read this wrong?

Jeff

JAG, what is your technique for checking the fuel vents? I have been wondering myself besides just probing the end for daubers.

Personal opinion here. I like to remove wing root covers on my high wing cessnas. Wing attachment bolts there. Besides bolts being pretty important, those covers aren’t the greatest at keeping rain/water out and bolts/wing attachments at risk for corrosion. Plus a stress point. Best to be eyeballed. I put some ACF-50 on them. A corrosion problem discovered late there could get pretty expensive.

Vent valve test
 

To check my fuel vent and vent valve, I have a 6ft piece of surgical tubing and a glass of water (or Costco bottle of water). I put the surgical tubing over the vent line on the trailing edge vent line at the wing tip. Next, I take a deep breath and blow into the other end of the tubing. If the air goes into the tanks (no resistance to my blowing), I know the vent is clear to the tank. Now, the next step I cheat a little...I take my compressor nozzle, and give a short shot into the tubing (simulating a real deep breath - I do this so I don't pass out), which slightly pressurizes your fuel tanks, then stick the end of the hose into the glass of water or bottle, and see if it bubbles. If it does, you know the vent valve weep hole is also doing its job of releasing pressure as well. if you have a fuel cap that does not seal well, your breath alone may not be enough to pressurize the tank (found that out the first time).

The main thing I am concerned with is the first part of the test - ensuring good flow of air into the tank. Small bugs can tend to block this line and that can cause issues with fuel flow or worse, collapsed tank.

Jeff

On my last flight as I made a hard right turn onto the runway, I noticed fuel streaming out of the left wing tip fuel tank vent line. Once the turn was completed the streaming stopped. I plan to do the testing as suggested in this thread and should it fail, has anyone recently replaced or overhauled their vent line check valves? If so, any information/help would be appreciated.

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

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.

Feedback
 

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

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

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.

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.