Hello.

Recently bought an airplane from a friend that has not been flown for 4 years. Its an Avonds F15. Builts very nicely and in pristine condtion. Its got 8 doors with 6 being main doors. These are operated with UP 2 and UP 4 valves in tandem. The UP 4 being the secondary valve to keep one set of main door open when the gears are down. The other doors will close. I find that the UP 4 valve won't keep these main doors OPEN. The moment I pressurise the system, these doors will close even when the mains are down and touch the struts. I have gone through the entire plumbing and everything is connected correctly with no leaks. Basically the UP 4 is not sending a signal to EVER open the door. The UP 4 manual is only a schematic and it doesn't show how to adjust anything. That being said, this airplane was functioning perfectly when it was flown last (4 years ago). Could the UP 4 valve be jammed? I thought it was a static secondary valve with no moving parts. The UP 2 that is feeding the signal pressure is functioning perfectly. Any suggestions?

Thanks
Anurag

I the UP 4 has a "slider" valve in it that is likely stuck. I have one on my Euro Sport and I believe that you can get to the slider by removing the two screws on the one end and taking out the circular "door" that the screws hold in. Then you should be able to break the slider free, lube it up a bit, and it should work fine...

Bob

If that does not work, I would give John a call or send him an email. Model Aviation products bought out Ultra Precision. He provides excellent product support!John Wiebe[email protected](204) 324-9741

My Dan Gill panther uses same system for nose doors. Sometimes you need to open valves and lube with dow 55 don't use other products. BVM stuff will destroy the seals

Buy a couple of spare valves now and send in yours for maintenance.

I agree, MAP is doing a fine job with the UP line.

You are incorrect on your your plumbing/sequence thought process. The U.P. 4 valve operates the gear and the doors that close when the gear is down. ( Like the inner clam shell doors on a P-51 Mustang ). The U.P. 2 valve's job is the keep doors open when the gear is down.
It can be very confusing... Hope this helps...

Dan.

Thanks guys. I opened up the valve and it was indeed sticky. I have now cleaned it up and lubed it. With the spring inside, it moves nicely. BUT... when connected to the system, it still won't open the doors...No matter what I do, the doors stay closed. There is no air coming from the door open nozzle during sequencing...however the plunger moves smoothly when opened up... Im stumped.

Do those needle valves actually TOUCH and restrict the moving part inside? How are those meant to be adjusted?

Are you getting air out of the UP2 to feed the UP4?
The needles allow more air through if you open, less close...like a carb needle. Loosen the nut first and hold the needle while you tighten the locking nut or it will turn with the nut.

Yes Dave, I am getting the control signal (air) from the UP 2 gear DOWN tube to the input of the UP 4. The UP 4 has its own AIR in as well. Im thinking perhaps the UP 4 doesn't needs its own AIR IN?

OK, I have checked and rechecked. There is no air coming out from the UP 4 DOOR OPEN nipple during the sequencing. The DOOR CLOSE nipple on the UP 4 has continuous pressure throughout both the cycles. I don't know what I am missing?

What pressure are you trying on the system?

Also when the cycle is trying to close the doors, pinch the airline to that side of the cylinders to remove the pressure forcing them shut

I am telling you, if that oring gets damaged/swollen/rots, no amount of lubing or trickery will fix it.

You are right Matt. Its just stuck, won't move even with 120psi. however it moves with my finger when screwed. Strange. Will change to electronic valves.

I personally would not do that but just order new valves and have your existing ones serviced as backup spares. I have had just as many hassles with electric valves.

I will take the UP valves if you are going to throw them out!

EDIT: I have reason to believe turbine oil does a number on these valve orings. Get MAP to send you some spare Orings and some DOW lube and try to fix yourself is a viable option as well

I would replace UP4. Way cheaper option and my Panther is now over 10 years old and still working

More then likely, since the jet has set for 4 years you have an internal leak in one or more of the cylinders. Either on the doors or the gear. Only way to find it is to pressurize the system and start pinching off lines in to the different areas on the jet then try the gear until you isolate it. You will find which cylinder is leaking when you pinch it off the system will work. The Up valves work great but you can not have any internal cylinder leak by or it plays havoc with them.
Joe Lewis
Kingtech
K-80, K-140, K-180
Owner

Joe makes a great point, to test you need to isolate potential "exhaust" points that fool the internal spool valve.

Air blowing by the retract cylinder piston is the usual culprit.

And don't use BVM quick lube to try to fix a leak in the cylinder, that stuff will degrade the UP oring.

All good points. Also check the door cylinder for blow by. I have seen this especially on models that have sat a while

Maybe im crazy but you sure the pipes for the doors are on the right spot on the UP2 valve