How well do your retracts hold air?
08-29-2014, 07:50 AM
#1
How well do your retracts hold air?
I've seen quite a bit of variation between a couple of my models with regards to how well they hold air. And yes, I realize that if I was using electric retracts I wouldn't lose any air at all :^)
One of my jets will hold air over night without appearing to have dropped in pressure at all while my latest project seems to want to lose air at a rate of about 5psi in 10 minutes... I've been through all the air lines checking for leaks with soapy water and can't find anything. I've isolated the circuit for the doors by disconnecting the lines and plugging the valves and that didn't seem to make a difference in the rate of air loss. I did the same for the retracts them selves and still couldn't find the source of the leak. At this point, I moved to the input side of things, and checked air lines, connections to the valve inputs, fill connectors and air tanks with soapy water and still no joy.. I'm pretty well out of ideas at this point but I suspect I must have missed something.
Since the model has gear fail safe that will drop the gear if the pressure drops to 50PSI and my typical flight times of 7 minutes, maybe 15 minutes elapsed time since filling, even with long take off delays at a jet rally, I really can't see this being a major issue but would still like to find the source of the leak if possible.
I've basically checked all the connections, isolated the door cylinders and the wheel cylinders.. Any suggestions as to what may be going on would be appreciated..
One of my jets will hold air over night without appearing to have dropped in pressure at all while my latest project seems to want to lose air at a rate of about 5psi in 10 minutes... I've been through all the air lines checking for leaks with soapy water and can't find anything. I've isolated the circuit for the doors by disconnecting the lines and plugging the valves and that didn't seem to make a difference in the rate of air loss. I did the same for the retracts them selves and still couldn't find the source of the leak. At this point, I moved to the input side of things, and checked air lines, connections to the valve inputs, fill connectors and air tanks with soapy water and still no joy.. I'm pretty well out of ideas at this point but I suspect I must have missed something.
Since the model has gear fail safe that will drop the gear if the pressure drops to 50PSI and my typical flight times of 7 minutes, maybe 15 minutes elapsed time since filling, even with long take off delays at a jet rally, I really can't see this being a major issue but would still like to find the source of the leak if possible.
I've basically checked all the connections, isolated the door cylinders and the wheel cylinders.. Any suggestions as to what may be going on would be appreciated..
Last edited by wfield0455; 08-29-2014 at 07:53 AM.
08-29-2014, 08:56 AM
#4
If my gear wont hold 140psi for 24hrs the airplane doesnt get flown. My last build took 3 days to pinpoint the leaks, but it will hold 120psi (what i operate at) for over a week with no discernable drop.
you didnt mention what valve you are using, but if it is a UP valve, it would be worth your while to remove the the valve spool and the door timing spool. I have had three of those valves now with metal shavings that caused an internal leak of the valve.
you didnt mention what valve you are using, but if it is a UP valve, it would be worth your while to remove the the valve spool and the door timing spool. I have had three of those valves now with metal shavings that caused an internal leak of the valve.
08-29-2014, 10:50 AM
#6
First, thanks to everyone that has replied. To answer the question about which valve I'm using, it's an Airpower EVSD-5U-PRO valve and the pressure gauge is internal. As for disconnecting lines vs using hemostats, since I have Festos on all ports of the valve, it seemed just as easy to disconnect the lines and install blanking plugs in the valve to tell if the gear cylinder circuit or door cylinder circuit was leaking. Disconnecting / blocking both the gear and door circuits didn't appear to make much difference. Since my first post, I went back to take a closer look at the tank and fill valve side of things. I found one of the lines to the fill valve would leak if I applied slight pressure to it I took care of that issue and that slowed the leak down further but didn't stop it completely. I now suspect that the fill valve itself may be leaking slightly. Since I have a spare fill fitting, I blocked that off and screwed it onto the fill value to seal it and see if that completely stops the leak on the input side of things. I just started that test and if it now holds air for an hour with no loss, I'll declare victory on the fill / tank side and then start reconnecting thing one at a time and repeating the leak test. I think the goal of holding air for 24 hours without loss is a good one and that is what I'm shooting. I suspect that if I can get it to hold air for an hour, it will probably hold it for 24 hours too,
08-29-2014, 11:56 AM
#7
My Behotec set ups hold air months, Xcalibur gear, weeks, BVM BobCat, weeks, Any air leak will get worse, I have the minimum number of joints, don't build a model with "service" joints, if you have to disassemble, replace tube or add joints then!
No air gauge, they and the three joints can leak.
More info on gear type and make would help.
No air gauge, they and the three joints can leak.
More info on gear type and make would help.
08-29-2014, 11:57 AM
#8
On the jet, both my brake and retrac systems hold the same air pressures for weeks. Guess I was lucky. But, I did wire-tie every connection and they are only in their first season with about 60 flights on them.
On the P-40's retracs, if the air pressure lasts an hour, I am lucky, I am currently going thru that system to see if I can improve the duration there. I think the cylinders' O-rings got dried out. Once I lubed a cylinder O-ring, that gear got stiffer to operate. I know I now have a better seal. But, ... now it takes a bit more air pressure for it to operate. Still froggin' around on this system.
On the P-40's retracs, if the air pressure lasts an hour, I am lucky, I am currently going thru that system to see if I can improve the duration there. I think the cylinders' O-rings got dried out. Once I lubed a cylinder O-ring, that gear got stiffer to operate. I know I now have a better seal. But, ... now it takes a bit more air pressure for it to operate. Still froggin' around on this system.
08-29-2014, 11:59 AM
#9
Hi Wayne,
I always start with the supply. Just the air tank, the fill valve and the gauge all isolated (in your case the fill valve, the tank and any T fillings).
As for pulling the lines out and putting in blanking plugs, what if your plugs seal better than your lines do? I would just use the hemostats and not introduce an unknown (just me)
I would think 1 hour holding air is fine, make sure and verify that both gear up and down. I hear about guys that don't lose air for a month or a decade or whatever, they are better modelers than I am. I usually shoot for an hour or so.
I always start with the supply. Just the air tank, the fill valve and the gauge all isolated (in your case the fill valve, the tank and any T fillings).
As for pulling the lines out and putting in blanking plugs, what if your plugs seal better than your lines do? I would just use the hemostats and not introduce an unknown (just me)
I would think 1 hour holding air is fine, make sure and verify that both gear up and down. I hear about guys that don't lose air for a month or a decade or whatever, they are better modelers than I am. I usually shoot for an hour or so.
08-29-2014, 12:27 PM
#10
Hi Wayne,
I always start with the supply. Just the air tank, the fill valve and the gauge all isolated (in your case the fill valve, the tank and any T fillings).
As for pulling the lines out and putting in blanking plugs, what if your plugs seal better than your lines do? I would just use the hemostats and not introduce an unknown (just me)
I would think 1 hour holding air is fine, make sure and verify that both gear up and down. I hear about guys that don't lose air for a month or a decade or whatever, they are better modelers than I am. I usually shoot for an hour or so.
I always start with the supply. Just the air tank, the fill valve and the gauge all isolated (in your case the fill valve, the tank and any T fillings).
As for pulling the lines out and putting in blanking plugs, what if your plugs seal better than your lines do? I would just use the hemostats and not introduce an unknown (just me)
I would think 1 hour holding air is fine, make sure and verify that both gear up and down. I hear about guys that don't lose air for a month or a decade or whatever, they are better modelers than I am. I usually shoot for an hour or so.
08-29-2014, 01:15 PM
#11
I find that when I use electronic valves, my set up doesn't hold air as long. My F4 with UP valves with hold air for weeks. My CARF Hawks with electronic valves will hold air for a few hours. They might hold it longer if the receiver were left on but, I think they must leak when not powered. Anyway as long as your system holds air reliably for the duration of a flight, I don't really see a problem.
Mike
Mike
08-29-2014, 02:41 PM
#12
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When I build any plane, I always put some BVM air cyl lube in every air cylinder regardless of function. Then I almost always use electronic air valves either
JetTronics or the ones from Xicoy. I have never had any leaking problems with the electronic ones ( so far) . Then I check EVERY joint with some sort of "leak-tec"
which is just soapy water ( sold under many names) and if there are any bubbles anywhere, that component is changed out. I no longer use any plastic T or Y joints
as these are problematic.. use just brass or metal ones. ALSO you cannot use the airlines from Dreamworks that come bonded together and then you must peel them apart.
If inserted into any festo type fitting as where these lines are "peeled" apart.. it leaves a small flat spot which will most likely leak in the ID of the festo. These airlines CAN be used however
if a "barb" type fitting is uded since these go on the inside of the tube bore. Using these techniques I have had very good luck with air systems in many planes for many years...
P.S. it is also important to test the exhaust ports on whatever air valve you use activate UP then DOWN... this will detect "blow-through" leaks in any air cylinder where the air is sneaking by it's internal
O-ring and escaping out the feed line on the opposite side of that cylinder. If you have leaks of this type the cylinder has to be opened up and cleaned and it's internal O-ring replaced
or if that is not possible.. the entire cylinder has to be replaced.
JetTronics or the ones from Xicoy. I have never had any leaking problems with the electronic ones ( so far) . Then I check EVERY joint with some sort of "leak-tec"
which is just soapy water ( sold under many names) and if there are any bubbles anywhere, that component is changed out. I no longer use any plastic T or Y joints
as these are problematic.. use just brass or metal ones. ALSO you cannot use the airlines from Dreamworks that come bonded together and then you must peel them apart.
If inserted into any festo type fitting as where these lines are "peeled" apart.. it leaves a small flat spot which will most likely leak in the ID of the festo. These airlines CAN be used however
if a "barb" type fitting is uded since these go on the inside of the tube bore. Using these techniques I have had very good luck with air systems in many planes for many years...
P.S. it is also important to test the exhaust ports on whatever air valve you use activate UP then DOWN... this will detect "blow-through" leaks in any air cylinder where the air is sneaking by it's internal
O-ring and escaping out the feed line on the opposite side of that cylinder. If you have leaks of this type the cylinder has to be opened up and cleaned and it's internal O-ring replaced
or if that is not possible.. the entire cylinder has to be replaced.
Last edited by geh3; 08-29-2014 at 02:47 PM.
08-29-2014, 07:34 PM
#13
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If my gear wont hold 140psi for 24hrs the airplane doesnt get flown. My last build took 3 days to pinpoint the leaks, but it will hold 120psi (what i operate at) for over a week with no discernable drop.
you didnt mention what valve you are using, but if it is a UP valve, it would be worth your while to remove the the valve spool and the door timing spool. I have had three of those valves now with metal shavings that caused an internal leak of the valve.
you didnt mention what valve you are using, but if it is a UP valve, it would be worth your while to remove the the valve spool and the door timing spool. I have had three of those valves now with metal shavings that caused an internal leak of the valve.
If you run out of air...roll inverted and put the gear up with the air you have left.......then head for the grass and keep the gear up!
It is not a perfect world. Nobody looks at the bottom of your plane when it is sitting on the ground anyways.
Jets...........more money.........your call. I've flown them all....with and without leaks.
Sierra and BVM make/sell the best valves on the market.
Last edited by Speedy-Gonzales; 08-29-2014 at 07:57 PM.
08-29-2014, 08:12 PM
#14
Well......you can be an extremist....or you can know you limitations and go fly. The implementation of caution knowing that you have a minute leak is within the realm of your flight envelope. My rule is 10 PSI over 10 minutes is allowable. Anything over that is not and you must keep leaks under control and observation. On a hot day.....be very cautious. On any day with a leak....be cautious and use common sense. 140 PSI is over the top. 120-110 is the norm for me before takeoff.
If you run out of air...roll inverted and put the gear up with the air you have left.......then head for the grass and keep the gear up!
It is not a perfect world. Nobody looks at the bottom of your plane when it is sitting on the ground anyways.
Jets...........more money.........your call. I've flown them all....with and without leaks.
Sierra and BVM make/sell the best valves on the market.
If you run out of air...roll inverted and put the gear up with the air you have left.......then head for the grass and keep the gear up!
It is not a perfect world. Nobody looks at the bottom of your plane when it is sitting on the ground anyways.
Jets...........more money.........your call. I've flown them all....with and without leaks.
Sierra and BVM make/sell the best valves on the market.
While my way isnt for everyone and is "extremist", i have never Not had my gear function 100% perfectly on every flight in over 7 years. Yes 140psi isnt necessary, but if it will hold that for 24hrs, it will hold 100-120psi just as easily for longer.
08-29-2014, 09:55 PM
#15
I hear about guys that don't lose air for a month or a decade or whatever, they are better modelers than I am. I usually shoot for an hour or so.
I have a little Bobcat 50 which will hold air for weeks. I'm usually reminded of that when preparing
the model for a day's flying when I turn on the receiver with the gear switch selected up!
- John.
08-29-2014, 11:06 PM
#16
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A lot of those airpower valves that I have used seem to leak internally and the systems that they are attached to are often complicated enough that it can be very difficult to find leaks, mostly because there are several.
One thing that makes a big difference is the quality of the retracts and the quality of the cylinders, most of the lower quality ones will leak through the system and the way to fix that is with lubrication.
another thing which is super important to mention here is the size of the tank your using, a small leak with a small tank is a big problem, a small leak with a large tank not so much but if your going to have leaks a small leak with several large tanks is your best option
if you want the system to hold 140psi over night just attach 35 large tanks to it, problem solved
seriously, I have had situations where I have lower quality or older cylinders and retracts that just leak, even with me messing with them, lubrication them and everything else they leak, and i'd much rather add an extra tank for $15 and 5 minutes work than replace everything, just depends on how much spare time and money I have on my hands
One thing that makes a big difference is the quality of the retracts and the quality of the cylinders, most of the lower quality ones will leak through the system and the way to fix that is with lubrication.
another thing which is super important to mention here is the size of the tank your using, a small leak with a small tank is a big problem, a small leak with a large tank not so much but if your going to have leaks a small leak with several large tanks is your best option
if you want the system to hold 140psi over night just attach 35 large tanks to it, problem solvedseriously, I have had situations where I have lower quality or older cylinders and retracts that just leak, even with me messing with them, lubrication them and everything else they leak, and i'd much rather add an extra tank for $15 and 5 minutes work than replace everything, just depends on how much spare time and money I have on my hands
08-30-2014, 04:03 PM
#18
Well, as luck would have it, I managed to yank defeat from the mouth of victory 
After almost completely disassembling the airplane Yesterday, I found that the Festo fittings that I had installed in the EVSD-5U-PRO air valve weren't quite tight enough and a couple were leaking where they threaded into the valve. Also the Airpower fill valve was leaking around the threads between it's upper and lower body. I snugged up the Festos and verified none of them were leaking and then opened up the fill valve, installed a new O-ring and reassembled it. IT seemed those things should take care of the air tank side of the system and a quick test with all that valve outputs clamped off confirmed it. I removed the hemostats I had used to clamp off the valve outputs and tested the system with the gear down and of course it was leaking badly. After carefully clamping off at each air cylinder I finally found one that appeared to be leaking. I disconnected it's air lines, added a few drops of BVM thin lube and replaced that section of line with new since it's ends were deformed from being pressed over the nipples and there wasn't enough tubing left to simply trim the ends. At this point the "gear down" side of things was working pretty well and would hold air well enough that it only dropped about 10 PSI per hour. Not ideal but a big improvement and I figured it would be safe to fly that way, I then retracted the gear and it was suddenly dropping 2 PSI per minute again Well, I had been working on this thing since 6:00AM and it was now about midnight so I decided to call it a day.
Early this morning I was back at it again and after testing all the fittings and air cylinders I couldn't find anything wrong. I eventually found a piece of line that was leaking where I had pinched it off with hemostats the day before. After replacing that section of line the "gear up" circuit seemed to be holding air about as well as the "gear down" side of things. Since I had everything disassembled, for the sake of being thorough, I decided I would lube the remaining door and wheel cylinders with a drop or 2 of BVM thin lube before starting to reassemble things. A quick test of the gear up and gear down circuits showed everything to be in order so I started putting the plane back together. Once I had all the airlines routed nicely and had remounted every thing it was time to do one final test before reinstalling the fuel tanks and the equipment tray that cover all of the air system. I pressurized the system for the final test and now the damned thing is leaking again at about 5PSI per MINUTE! I looked everything over carefully as I figured something must have simply become disconnected and it would probably be a simple fix. After about 45 minutes of inspecting things I couldn't find anything wrong. Since none of the connections seemed to be leaking I decided to test the valve again and clamped of all the outputs. This didn't slow the leak down at all so it had to be the air tank sode of things again or the valve it self. At this point it was starting to get the best of me so I decided to take a break. After I'd had a chance to relax a bit I removed the air valve, the tanks and the fill valve to check them one last time but there were no leaks to be found. Since I've isolated everything but the tank, fill valve and the valve itself and there were no leaks at any of the tank or fill valve connections, it seems the EVSD-5U-PRO valve was leaking internally...
I've been going straight out trying to finish this Jet in time for the Maine Jet Rally which starts next Thursday but with the holiday, etc, it seems doubtful that I'll be able to get a replacement valve by then. It's pretty disappointing but what can you do. At this point, I'm looking to make up a temporary replacement out of a couple of Jetronic dual valves and a Xicoy brake value that I have available. I'll use the sequencer in my Jeti DS16 to handle the doors and hopefully nothing will leak. I refuse to be beaten by this thing, it's going to be ready to fly by next Thursday one way or another.
To be continued....
After almost completely disassembling the airplane Yesterday, I found that the Festo fittings that I had installed in the EVSD-5U-PRO air valve weren't quite tight enough and a couple were leaking where they threaded into the valve. Also the Airpower fill valve was leaking around the threads between it's upper and lower body. I snugged up the Festos and verified none of them were leaking and then opened up the fill valve, installed a new O-ring and reassembled it. IT seemed those things should take care of the air tank side of the system and a quick test with all that valve outputs clamped off confirmed it. I removed the hemostats I had used to clamp off the valve outputs and tested the system with the gear down and of course it was leaking badly. After carefully clamping off at each air cylinder I finally found one that appeared to be leaking. I disconnected it's air lines, added a few drops of BVM thin lube and replaced that section of line with new since it's ends were deformed from being pressed over the nipples and there wasn't enough tubing left to simply trim the ends. At this point the "gear down" side of things was working pretty well and would hold air well enough that it only dropped about 10 PSI per hour. Not ideal but a big improvement and I figured it would be safe to fly that way, I then retracted the gear and it was suddenly dropping 2 PSI per minute again Well, I had been working on this thing since 6:00AM and it was now about midnight so I decided to call it a day.Early this morning I was back at it again and after testing all the fittings and air cylinders I couldn't find anything wrong. I eventually found a piece of line that was leaking where I had pinched it off with hemostats the day before. After replacing that section of line the "gear up" circuit seemed to be holding air about as well as the "gear down" side of things. Since I had everything disassembled, for the sake of being thorough, I decided I would lube the remaining door and wheel cylinders with a drop or 2 of BVM thin lube before starting to reassemble things. A quick test of the gear up and gear down circuits showed everything to be in order so I started putting the plane back together. Once I had all the airlines routed nicely and had remounted every thing it was time to do one final test before reinstalling the fuel tanks and the equipment tray that cover all of the air system. I pressurized the system for the final test and now the damned thing is leaking again at about 5PSI per MINUTE! I looked everything over carefully as I figured something must have simply become disconnected and it would probably be a simple fix. After about 45 minutes of inspecting things I couldn't find anything wrong. Since none of the connections seemed to be leaking I decided to test the valve again and clamped of all the outputs. This didn't slow the leak down at all so it had to be the air tank sode of things again or the valve it self. At this point it was starting to get the best of me so I decided to take a break. After I'd had a chance to relax a bit I removed the air valve, the tanks and the fill valve to check them one last time but there were no leaks to be found. Since I've isolated everything but the tank, fill valve and the valve itself and there were no leaks at any of the tank or fill valve connections, it seems the EVSD-5U-PRO valve was leaking internally...
I've been going straight out trying to finish this Jet in time for the Maine Jet Rally which starts next Thursday but with the holiday, etc, it seems doubtful that I'll be able to get a replacement valve by then. It's pretty disappointing but what can you do. At this point, I'm looking to make up a temporary replacement out of a couple of Jetronic dual valves and a Xicoy brake value that I have available. I'll use the sequencer in my Jeti DS16 to handle the doors and hopefully nothing will leak. I refuse to be beaten by this thing, it's going to be ready to fly by next Thursday one way or another.
To be continued....
Last edited by wfield0455; 08-30-2014 at 04:13 PM.
08-30-2014, 04:34 PM
#19
After reading this thread I decided to check my Firebird's air system. I haven't done anything with this airplane since fall September of last year. I looked at the 3 systems, (gear, doors, brakes) and they were all between 85 and 95psi. Not bad considering I fill to 100psi and I haven't filled them since September!!!! My Kingcat used to be the same way before I sold it, the gear would hold air for over a year without any problem. My bobcat will hold for a couple months and my Raptor had a slow leak on one of the guages but would still be ok overnight.
08-30-2014, 06:16 PM
#20
Ok, I may have spoken too soon about the EVSD-5U-PRO leaking internally. Since I checked every fitting at the tank and fill valve with soapy water and I couldn't find any leaks, I assumed the valve must be leaking internally. It was really bothering me that the valve would fail after initially testing Ok so I decided to run one more test. I added a longer line, pressurized the tank and then submerged the tank and fill valve in the kitchen sink and low and behold, the AIRTANK leaks around the crimp.
Now the question is, since it may be difficult to get a new airtank in time, has anyone had any success fixing a leak in an airtank?
Now the question is, since it may be difficult to get a new airtank in time, has anyone had any success fixing a leak in an airtank?
08-30-2014, 06:17 PM
#21
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Well, as luck would have it, I managed to yank defeat from the mouth of victory After almost completely disassembling the airplane Yesterday, I found that the Festo fittings that I had installed in the EVSD-5U-PRO air valve weren't quite tight enough and a couple were leaking where they threaded into the valve. Also the Airpower fill valve was leaking around the threads between it's upper and lower body. I snugged up the Festos and verified none of them were leaking and then opened up the fill valve, installed a new O-ring and reassembled it. IT seemed those things should take care of the air tank side of the system and a quick test with all that valve outputs clamped off confirmed it. I removed the hemostats I had used to clamp off the valve outputs and tested the system with the gear down and of course it was leaking badly. After carefully clamping off at each air cylinder I finally found one that appeared to be leaking. I disconnected it's air lines, added a few drops of BVM thin lube and replaced that section of line with new since it's ends were deformed from being pressed over the nipples and there wasn't enough tubing left to simply trim the ends. At this point the "gear down" side of things was working pretty well and would hold air well enough that it only dropped about 10 PSI per hour. Not ideal but a big improvement and I figured it would be safe to fly that way, I then retracted the gear and it was suddenly dropping 2 PSI per minute again Well, I had been working on this thing since 6:00AM and it was now about midnight so I decided to call it a day.
Early this morning I was back at it again and after testing all the fittings and air cylinders I couldn't find anything wrong. I eventually found a piece of line that was leaking where I had pinched it off with hemostats the day before. After replacing that section of line the "gear up" circuit seemed to be holding air about as well as the "gear down" side of things. Since I had everything disassembled, for the sake of being thorough, I decided I would lube the remaining door and wheel cylinders with a drop or 2 of BVM thin lube before starting to reassemble things. A quick test of the gear up and gear down circuits showed everything to be in order so I started putting the plane back together. Once I had all the airlines routed nicely and had remounted every thing it was time to do one final test before reinstalling the fuel tanks and the equipment tray that cover all of the air system. I pressurized the system for the final test and now the damned thing is leaking again at about 5PSI per MINUTE! I looked everything over carefully as I figured something must have simply become disconnected and it would probably be a simple fix. After about 45 minutes of inspecting things I couldn't find anything wrong. Since none of the connections seemed to be leaking I decided to test the valve again and clamped of all the outputs. This didn't slow the leak down at all so it had to be the air tank sode of things again or the valve it self. At this point it was starting to get the best of me so I decided to take a break. After I'd had a chance to relax a bit I removed the air valve, the tanks and the fill valve to check them one last time but there were no leaks to be found. Since I've isolated everything but the tank, fill valve and the valve itself and there were no leaks at any of the tank or fill valve connections, it seems the EVSD-5U-PRO valve was leaking internally...
I've been going straight out trying to finish this Jet in time for the Maine Jet Rally which starts next Thursday but with the holiday, etc, it seems doubtful that I'll be able to get a replacement valve by then. It's pretty disappointing but what can you do. At this point, I'm looking to make up a temporary replacement out of a couple of Jetronic dual valves and a Xicoy brake value that I have available. I'll use the sequencer in my Jeti DS16 to handle the doors and hopefully nothing will leak. I refuse to be beaten by this thing, it's going to be ready to fly by next Thursday one way or another.
To be continued....
After almost completely disassembling the airplane Yesterday, I found that the Festo fittings that I had installed in the EVSD-5U-PRO air valve weren't quite tight enough and a couple were leaking where they threaded into the valve. Also the Airpower fill valve was leaking around the threads between it's upper and lower body. I snugged up the Festos and verified none of them were leaking and then opened up the fill valve, installed a new O-ring and reassembled it. IT seemed those things should take care of the air tank side of the system and a quick test with all that valve outputs clamped off confirmed it. I removed the hemostats I had used to clamp off the valve outputs and tested the system with the gear down and of course it was leaking badly. After carefully clamping off at each air cylinder I finally found one that appeared to be leaking. I disconnected it's air lines, added a few drops of BVM thin lube and replaced that section of line with new since it's ends were deformed from being pressed over the nipples and there wasn't enough tubing left to simply trim the ends. At this point the "gear down" side of things was working pretty well and would hold air well enough that it only dropped about 10 PSI per hour. Not ideal but a big improvement and I figured it would be safe to fly that way, I then retracted the gear and it was suddenly dropping 2 PSI per minute again Well, I had been working on this thing since 6:00AM and it was now about midnight so I decided to call it a day.Early this morning I was back at it again and after testing all the fittings and air cylinders I couldn't find anything wrong. I eventually found a piece of line that was leaking where I had pinched it off with hemostats the day before. After replacing that section of line the "gear up" circuit seemed to be holding air about as well as the "gear down" side of things. Since I had everything disassembled, for the sake of being thorough, I decided I would lube the remaining door and wheel cylinders with a drop or 2 of BVM thin lube before starting to reassemble things. A quick test of the gear up and gear down circuits showed everything to be in order so I started putting the plane back together. Once I had all the airlines routed nicely and had remounted every thing it was time to do one final test before reinstalling the fuel tanks and the equipment tray that cover all of the air system. I pressurized the system for the final test and now the damned thing is leaking again at about 5PSI per MINUTE! I looked everything over carefully as I figured something must have simply become disconnected and it would probably be a simple fix. After about 45 minutes of inspecting things I couldn't find anything wrong. Since none of the connections seemed to be leaking I decided to test the valve again and clamped of all the outputs. This didn't slow the leak down at all so it had to be the air tank sode of things again or the valve it self. At this point it was starting to get the best of me so I decided to take a break. After I'd had a chance to relax a bit I removed the air valve, the tanks and the fill valve to check them one last time but there were no leaks to be found. Since I've isolated everything but the tank, fill valve and the valve itself and there were no leaks at any of the tank or fill valve connections, it seems the EVSD-5U-PRO valve was leaking internally...
I've been going straight out trying to finish this Jet in time for the Maine Jet Rally which starts next Thursday but with the holiday, etc, it seems doubtful that I'll be able to get a replacement valve by then. It's pretty disappointing but what can you do. At this point, I'm looking to make up a temporary replacement out of a couple of Jetronic dual valves and a Xicoy brake value that I have available. I'll use the sequencer in my Jeti DS16 to handle the doors and hopefully nothing will leak. I refuse to be beaten by this thing, it's going to be ready to fly by next Thursday one way or another.
To be continued....
You're a patient man Wayne.... I think after all that time and trouble, I would have ripped out the entire system and gone electric
I'm glad you found the culprit.
Regards,
Mort
08-30-2014, 07:52 PM
#22
My Feedback: (1)
Ok, I may have spoken too soon about the EVSD-5U-PRO leaking internally. Since I checked every fitting at the tank and fill valve with soapy water and I couldn't find any leaks, I assumed the valve must be leaking internally. It was really bothering me that the valve would fail after initially testing Ok so I decided to run one more test. I added a longer line, pressurized the tank and then submerged the tank and fill valve in the kitchen sink and low and behold, the AIRTANK leaks around the crimp.
Now the question is, since it may be difficult to get a new airtank in time, has anyone had any success fixing a leak in an airtank?
Now the question is, since it may be difficult to get a new airtank in time, has anyone had any success fixing a leak in an airtank?
Do you have a local hobby shop close by that might keep some Robart air tanks in stock?
If you try to fix it I would suggest soaking the outside of the leaking area with Hysol (Aeropoxy) and pulling a slight vacuum on the tank in order to pull the adhesive into the leaking voids. Since I have not actually repaired a leaking tank this way I can't gaurantee that fix will hold, but I think it would be your best chance at success.
Good luck.
08-31-2014, 03:34 AM
#23
What size tank do you need?
Do you have a local hobby shop close by that might keep some Robart air tanks in stock?
If you try to fix it I would suggest soaking the outside of the leaking area with Hysol (Aeropoxy) and pulling a slight vacuum on the tank in order to pull the adhesive into the leaking voids. Since I have not actually repaired a leaking tank this way I can't gaurantee that fix will hold, but I think it would be your best chance at success.
Good luck.
Do you have a local hobby shop close by that might keep some Robart air tanks in stock?
If you try to fix it I would suggest soaking the outside of the leaking area with Hysol (Aeropoxy) and pulling a slight vacuum on the tank in order to pull the adhesive into the leaking voids. Since I have not actually repaired a leaking tank this way I can't gaurantee that fix will hold, but I think it would be your best chance at success.
Good luck.
Last edited by wfield0455; 08-31-2014 at 03:41 AM.
08-31-2014, 04:20 AM
#24
My Feedback: (5)
Join Date: Dec 2011
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Wayne,
If it is any consulation I'll be attending the Maine Jet Rally and always carry a set of spare air tanks with me-Robart and others, various sizes. Look me up in the non-reserved "pop-up tent" area.
Rgds,
Art ARRO
If it is any consulation I'll be attending the Maine Jet Rally and always carry a set of spare air tanks with me-Robart and others, various sizes. Look me up in the non-reserved "pop-up tent" area.
Rgds,
Art ARRO
08-31-2014, 05:53 AM
#25
My Feedback: (1)
I have had my share of leaking air tanks also. I have tried all the repairs. Most don't work.
I wish some company would try and produce a high quality air tank even if it cost more.
My feelings are this is a weak link that needs to be addressed.
The way the nipples are fitted are sub standard in my opinion.
Stan
I wish some company would try and produce a high quality air tank even if it cost more.
My feelings are this is a weak link that needs to be addressed.
The way the nipples are fitted are sub standard in my opinion.
Stan