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Help with pneumatic electronic valves

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Old 02-12-2018, 09:41 AM
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c_makhija
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Default Help with pneumatic electronic valves

Hi Guys,

Been flying my Skygate Hawk over the last 2 years, got around 25 flights on it so far.
Today had 4 flights on it. On 3 flights out of the 4 the gear did not retract. The gear so far has been working flawless with around 125 PSI of pressure.
No leaks in the up or down positions. And all 3 individual gears operate smoothly when directly connected to the air pump.
Only thing that comes to mind is a sticky valve. Is it possible these valves open partially which is not allowing enough volume of air to go to the cylinders, or could there be any other reason.
Changing the valve would be least of my worries.

Thanks
Chatty.
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Old 02-12-2018, 09:48 AM
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Dave Wilshere
 
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Did it partly retract? Were you taking off faster than normal, leaving it longer to retract the gear?
Speed is a big issue with the Hawk. Did the nose go?
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Old 02-12-2018, 11:02 AM
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c_makhija
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Yes Dave, it did partly retract. Rotation was in fact slightly earlier than normal to facilitate retraction, and gear selection as I saw the mains unstick. Nose gear partial retraction too.

BTW I was expecting you to be the first to reply😊
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Old 02-12-2018, 02:14 PM
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Dave Wilshere
 
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Predictable! ��

if you rig the model now, charge the air and operate, grab a leg each time, does there seem to be power pulling the legs up? Any venting?
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Old 02-12-2018, 02:42 PM
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I had random valve problems on my SM F-16. Could never duplicate till it would happened again. After a complete tear down to install an new power distribution system I would the red wire on one valve had a bad crimp from the factory and the wire was loose in the crimp pin and would easily slide out. Wa...la...Problem duplicated on the bench. Nearly cost me the jet several times with a gear up landing.
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Old 02-13-2018, 02:07 PM
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Quote:
Originally Posted by Dave Wilshere View Post
Predictable! ��

if you rig the model now, charge the air and operate, grab a leg each time, does there seem to be power pulling the legs up? Any venting?
Dave.. off on a flight, back home only Friday. Will check and revert.
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Old 02-14-2018, 11:24 AM
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David Gladwin
 
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I have two Airworld Hawks Jettronics gear valves work perfectly at 10 bar,150 psi .sluggish at 125 psi.

My Skygate Hawkgear works perfectly at10 bar using the Intairco valve unit which also includes speed control , superb unit !

However if your units used to work I suggest:
Injecting some BVM thin lube into your air system to lube the cylinders. Use a water trap in your compressor air line.
Cleaning all moving parts then applying BVM dry lube. This gives me perfect results and my guess is it will solve your problem!

David G.

Last edited by David Gladwin; 02-14-2018 at 10:58 PM.
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Old 02-15-2018, 11:57 AM
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Hello David,

Actually went up to 140 PSI for 2 flights with no luck. The gear when connected direct to the pump operates with minimal pressure and smooth.
Water trap has been there from day 1. Suspect the valve as even the nose did not retract.
Any experience with the JMP high flow mechanical valve?

Regards
Chatty.
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Old 02-15-2018, 12:55 PM
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Sometimes valves work best with lower pressures. They may be made to work against the air pressure when actuated. Does the gear work well with only 75 PSI? The BVM air valves are this way - mine were too slow at 100 PSI but work fine at 75 PSI.

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Old 02-15-2018, 01:49 PM
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I'm surprised that no one has suggested that you might have some crap stuck in the valve. I've seen that before causing slow, or no, gear retraction...

Do you have another spare valve around that you can put into the system temporarily and see how the gear works?

Bob
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Old 02-16-2018, 12:28 AM
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Quote:
Originally Posted by c_makhija View Post
Hello David,

Actually went up to 140 PSI for 2 flights with no luck. The gear when connected direct to the pump operates with minimal pressure and smooth.
Water trap has been there from day 1. Suspect the valve as even the nose did not retract.
Any experience with the JMP high flow mechanical valve?

Regards
Chatty.
Hi Chatty,
can only conclude itís the valve.

I have no experience with JMP but I guess it will be top quality.

However, as I said earlier Jet Tronics works perfectly on my AirWorld Hawks and the Intairco dual valve system, gear and doors, has proven perfect for my SkyGate Hawk !

So so itís a valve change!

David
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Old 02-16-2018, 06:36 AM
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These valves are highly susceptible to moisture. I know you say you have a trap but I will bet it is full of moisture. I did an experiment in Houston and the trap lasted less then one day before full of moisture. Best way to fill tanks is small scuba bottle with stage reduction for pressure
or change to mechanical valves like JMP UP style. Good luck with your diagnoses and gear working flying!!!!!
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Old 02-16-2018, 06:45 AM
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I only fill my air tanks from a small scuba tank, no moisture at all. Of course you need a regulator and pressure adjustable valve you can set to 100 PSI or so.

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Old 02-17-2018, 08:11 AM
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c_makhija
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Thanks Guys,

Valve changed. Need to assemble the hawk and see if there is any change. The problem is can actually be tested 100% in flight. This had the older orbit valves, now the evojet.

Regards
Chatty.
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Old 02-17-2018, 08:15 AM
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Quote:
Originally Posted by kevinthoele View Post
These valves are highly susceptible to moisture. I know you say you have a trap but I will bet it is full of moisture. I did an experiment in Houston and the trap lasted less then one day before full of moisture. Best way to fill tanks is small scuba bottle with stage reduction for pressure
or change to mechanical valves like JMP UP style. Good luck with your diagnoses and gear working flying!!!!!
Guess your right, will change to the JMP valve if this one does not deliver.
Been using the BVM mechanical valve for more than 10 years now in all my sport jets, never a hiccup.

Chatty.
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