Citabria fuel valves and tail wheels

A

aussie

New member
I have owned a 7KCAB for a year and wanted to share a little info with other owners. My tail wheel had a bad shimmy whenever I had someone in the back seat, even solo it would shimmy unless I did real perfect landing. I tried different tire pressures, but no change. The angle of the swivel plate had a negative angle of attack because of a sagging leaf spring, so I installed a new spring set which gave it a positive angle. The results were outstanding. I have not had one shimmy since, and it's lighter on the rudder pedals to taxi and more responsive, best investment ever. I was horrified to read about pilots pushing the stick forward to unload the tail wheel because of a shimmy when that can increase the risk of a ground loop, it's just not worth it for the sake of installing a new spring set.
My other info is about the fuel shut off valve. A.C does not have replacement valves for the old ones like on my '67 model, so I removed and dismantled it to see why it was leaking fuel on the floor. There is only one O ring in the valve that seals the shaft where it exits the front screw on housing. I found an exact match O ring Part Number AS3208-03 at an FBO. I cleaned up the whole valve, reassembled and pressure tested it. I've installed it and so far has not leaked at all, looks like a good fix. The alternative according to A.C is to weld new brackets and mount a new valve. I hope this helps someone out. Happy Flying!
 
Thanks for the info. Unloading the tailwheel to stop a shimmy in the Citabria/Decathelon series isn't a big deal, they don't have any real tendencies to bite you and are very directionally stable on the ground, but it's not something you want to get in the habit of if you ever intend to transition to more finicky airplanes. I wouldn't do it in the Great Lakes I fly for example.
 
I recently bought a 1969 7KCAB with metal spars and I really like this plane. I am also new to the forum. The fuel valve is not leaking but it is so tight that it can hardly be turned off/on so for now I just leave it on, and I think that is what the previous owner did. Do you think the O ring replacement and fuel lube of the valve will help this problem? Also, I had real bad shimmy as described and replaced the TW spring, and the Scott 3200 only had three of the five small springs in it so I added two more thereby making it as it came from the factory and the shimmy is completely gone now.
Thanks
Bill
 
More about fuel valves:
Beechcraft Muskaeteers and Beechcraft Sports used the same fuel valve. They have a Service Instruction No. 0364-289 rev.III
that details maintenance on these valves. They recommend using Dow Corning Molykote FS-1292 for the fuel valve lubricant.
I used Fuel lube (now called Easy Turn) in the past and it worked well, but I now use Molykote and I find that it lasts longer than the Fuel lube. The MS number for the "O" ring is MS29513-011, and the crush washer is AN900-13. (Some use a flat copper washer 13/16" ID, in place of the crush washer.)

I agree, if you have tail wheel shimmys, get a new spring pack!
Always buy from ACA whenever possible.

Bill B
 
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