Flop tube maintenance requirements

[Bateleur]

Danny King noted in this thread that replacing his flop tube every 5 years was a pain. It was a passing, matter of fact comment and were it necessary, I would tend to agree. My problem was that it was the first time I had heard this. Being just about ready to close up my left tank with a flop tube installed, I found myself stopping to re-think.

Danny?s comment made me go and do some additional research into flop tubes. Whilst Van's doesn't appear to state anywhere explicitly that flop tube's require periodic replacement, i.m.o. there is more than sufficient evidence to suggest that it would prudent to do so. The Extra 300 manual (chapter 28) details the flop tube replacement process and on many of the aerobatic and bi-plane forums, it appears to be general knowledge that the flop tube requires regular inspection and maintenance. It would seem that the flop tube hardens over time.

My plan was to install the flop tube left, standard pickup right - the flop was for "just incase" - if you understand my meaning. I'm about to close up the left tank and have now changed my plans. My left tank has all the mods required for the flop tube (in fact, the flop tube was actually fitted) but it now has a standard pickup installed. I figure that should I ever really need inverted capabilities in future (unlikely), then the level of effort required to replace the standard pick up with a flop tube will be only slightly more than that required for one of the ?periodic replacements? (considering that my tank was built for it in the first place).

I?m really not keen on having to rip off the fuel tank, open it up, replace the flop tube and re-seal every so often?

What has prompted this post though is the fact that Rick6a, in the same thread, is also unsure with regards the maintenance requirements for flop tubes. I didn?t want to hi-jack the thread but was hoping to get a little more info re the maintenance of flop tubes. Do you replace yours, don?t you, how long have you had them installed, can you still feed all your fuel from the respective tank, etc?

Info appreciated ? I?m about ready to close up my tank and it is now such that I could quite easily go either way!

[schristo@mac.com]

over time the flop tube will probably tend to get less flopy which is not an issue unless you are actually relying on it as a flop tube. the bigger issue is likely from the o-ring on the end of the weighted pickup... if it fails from routine use? or dries out and fails there could be wear to the inside of the tank skin and debris in the tank. if the o-ring stays wetted with fuel I suspect that it will be fine for much longer than 5 years... anyone have actual inspection results?

[RV8Squaz]

Originally Posted by schristo@mac.com

over time the flop tube will probably tend to get less flopy which is not an issue unless you are actually relying on it as a flop tube. the bigger issue is likely from the o-ring on the end of the weighted pickup... if it fails from routine use? or dries out and fails there could be wear to the inside of the tank skin and debris in the tank. if the o-ring stays wetted with fuel I suspect that it will be fine for much longer than 5 years... anyone have actual inspection results?

Reviving an old thread here to answer your question almost 9 years later. My flop tube was installed in 1999 and has been in service since 2007. The flop tube and o ring appear to be in excellent shape. But since I?ve got the tank opened up anyway I?m replacing the flop tube with a new hose and o ring. The o ring is a little hard but otherwise fine. The o ring did wear a little groove in the skin. I just filled the groove with a dab of sealant.

[TS Flightlines]

Just a note on this---TEFLON hose does not work well as it has a memory and doesnt flop. We get asked about this alot. Kahuna and I played with it about 5 years ago and no real joy. A REAL swivel fitting would be fabulous, but without the fabulous price. An industrial swivel hose end doesnt work because the ORing that seals the stem of the fitting to the nut, is stiff, wont allow the fitting to move free enough.

HUM---have a few ideas----I may play with this again--

Tom

[Larry DeCamp]

I have a new one in my circa 1999 RV4 project (acquired 2nd hand). Replaced the flop it with standard pickup for all the reasons above. If you need/want one real bad, contact me...Larry

[RV8Squaz]

Originally Posted by Larry DeCamp

I have a new one in my circa 1999 RV4 project (acquired 2nd hand). Replaced the flop it with standard pickup for all the reasons above. If you need/want one real bad, contact me...Larry

Thank you Larry. I don't need one. Tom is replacing the hose portion of the flop tube for me.