I'm having problems with my Robart retracts. When they're in the airplane it leaks all the air as soon as I start the engine I know this because I installed a Robart gage and it is very clear that the air is gone, but when are pulled out of the airplane, assembled, and submerge under water the're no leaks at all even under 100 psi.
Any thoughts on this problem?

Carlos

Make sure no part of your gear struts or wheels are hitting any part of the wheel wells when they are retracted. Sometimes this will cause a leak.

OR..... check with some dish soap at the connections when installed in the plane.

Every major air leak I've ever had, turned out to be a leaking fill valve.

I agree, the only leaking I have ever had is with Robart's one-piece Schaeder-type fill valve. I only use Robart's two piece set up now (a fill fixture plus a one way check valve).

Thanks

What do you know?, I do have the one-piece Schaeder-fill valve and I also have the new two piece fill one way valve that I was saving for another project. ( not any more )
I will change the old valve for the new one and do the soap test again.
Thank you all. I knew I could count with your help.

Carlos

Make sure the gear and Wheel has enough space when in the retracted(or down) position so that the retract goes through entire locking position or travel. I believe if the piston does not travel the entire length, you will get an air leak as the piston is constantly trying to hold the gear up. This is what happenned on my Roo, one wheel would rest on the Turbine hoses, and it would not lock up completely. The air would leak out very quickly, After moving the lines, the gear now holds pressure for days.

Must be an echo in here!!!LOL I think thats what i said in my first post. With less words. Ha Ha

Ok. The problem has not gone away.
Let me explain. At the field I put together the airplane gas it and charge the air retract system, start the engine and open the throttle for max RPM as I'm doing this I can watch the air meter go from 100 psi to 0 psi, it only takes about 40 sec. to deplete the air. The servo and the air valve are mounted on the side of the fuse and former. I'm thinking that the vibration from the engine is somehow moving the air valve or the servo to much for this to happen, remember this only happens when the engine is running and at no other time.
Do you think I need a new air valve?

The air valve that I have is old, the one you had to use wheel collars to set the travel distance.



Carlos

I'll bet Robart would like that valve for their museum!

Seriously, you may be on to something there. Replace the O-rings in the valve (if they still make them).

If you have some hemostats, just start going thru all the airlines until the leak stops. For example, clip off the line going to the MLG retracts. If it still leaks, clip off the NLG line. Still leaking?...

Just go thru the entire system with the hemostats. Does it leak when gear are down, or up and down? This can give you a hint to where it is leaking. If it leaks up and down, you may have multiple leaks, or manifold leak, or supply tank leak, or filler valve/gauge leak... It could very well be orings in the valve, as previously suggested...

Sounds like you are on the right track, with either the servo or the air valve moving.
Do the hemostats, with the engine running, and start at the fill valve, working your way out methodically. As far as I am concerned, the only way to troubleshoot a leaky air system is with hemostats, and you have to do it one piece at a time, starting at one end and working to the other. No shortcuts, unless you like repainting the bottom of your planes.

Thank you all for the good advices.

Ron. This afternoon I went to the field and did exactly what you suggested, I did it with the engine running for every single test at the end of all the testing I found out that the leakage was coming from the nose retract only when the engine was running, I also notice that the retract body was not seating flat but with a twist, this twist was pushing the retract shaft down making the air to leak.
G4guy you also gave me a good idea to solve this problem.
But I like to thank the members that responded promptly.
Thank you all.

Carlos

And 5 years later you helped me fix my problem too I love RCU

yeap!lots of "know how"[8D]