3278 Hydraulic Mystery solved 3281,82,83,87,88

05-03-2008, 03:48 AM

Fred Lohr | 3278 Hydraulic Mystery solved 3281,82,83,87,88

well, finally solved the mystery of why my spool valves kept getting stuck, but not exactly the way i would have wished. I took of on an afternoon flight and despite everything checking out on the ground experienced a failure of the hydraulic system shortly after takeoff. The flaps were up, and the gear partialy up when the pump quit. the pressure guage went to zero and the annuciator light for the pump would not go on no matter what. So now I'm stuck with gear half up/half down and -10 degrees flaps. thank goodness the hand pump put the gear down just as designed. After a few practice attempts at altitude, I picked 79 knots as my landing speed. that's coming in a bit hot, but above stall speed in my airplane. The nose is a higher with -10 flaps, but she stuck to the turf runway just fine and I had plenty of room to stop. Now the interesting part. When i took the pump apart, i found a fine powder of rust within the motor. some rust on the armature, some on the inside of the steel case, and a fine rusty powder down at the bottom. I surmise that the seal at the bottom eventually let a little of this stuff thru into the pump along the shaft and then into the fluid. i note that this motor was dunked once years ago, so maybe thats what started things. anyway, the thing is cleaned up and working again, but I am going to spring for a new pump or at least a new motor as this one was made by Oildyne in 1995. this also got me thinking about some way to use the handpump to deploy the flaps as well as the gear in the event of pump failure. Are there any builders who have manual valves controlling the flaps and gear rather than electrical? what kind/brand of valves did you use?

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Posted by Tom Saccio on May 03, 2008 at 23:34:20:

In Reply to: hydraulic mystery solved posted by fred lohr on May 03, 2008 at 21:39:50:

Some time ago Ted El-Hajj figured out how to lower and raise the flaps using the hand pump. It had something to do with turning the flap switch to the down or up position and then using the hand pump. I will contact him to get the specifics on just how to do it and then I will post it tomorrow. Tom Saccio N516SW

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Posted by Tony Jurcan on May 04, 2008 at 12:40:58:

In Reply to: hydraulic mystery solved posted by fred lohr on May 03, 2008 at 21:39:50:

Fred, Both Wally Weller and myself are using Lake Amphibian manual selector valves. Wally's are mounted below his panel using the original Lake handles and mine are in a center console between the seats. Does anyone have a source for proximity switches to be used for indicating position of landing gear? Tony

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Posted by Tom Saccio on May 04, 2008 at 22:55:45:

In Reply to: hydraulic mystery solved posted by fred lohr on May 03, 2008 at 21:39:50:

The flaps could be retracted by Holding down the flap switch and using the hand pump. This will lower the flaps as much as you want. If the switch is in the up position then the flaps will go up as you pump the handle. The same holds true with the landing gear. Tom Saccio

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Posted by fred lohr on May 07, 2008 at 22:30:04:

In Reply to: hydraulic mystery solved posted by fred lohr on May 03, 2008 at 21:39:50:

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Posted by fred lohr on May 07, 2008 at 22:48:23:

In Reply to: Re: hydraulic mystery solved posted by fred lohr on May 07, 2008 at 22:30:04:

Now that i have played around with this thing, i realize that deploying the flaps with the hand pump is no big deal if you have power to the switches. this is something we should all do and I should have done prior to my pump quitting in flight. in the set up with elctrically activated spool valves, the procedure is to move the handle on the pump to the gear down position, put gear down,(or up for water), make sure the gear is down(or up), put the electrical switch in the gear down(up) position, pump some pressure(this can be seen on the guage) and then move the flaps down. This does not work if there is no power at all to the switches. the reason is that the fluid cannot move from the gear circut to the flap circut if either valve is closed. The "manual" system came out as an option in 2001. It looks like this would be a system that would work with no electrical power at all. I would like to see one of these manifold/switch setups. have any of the newer kit builders got any photos of this setup?

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Posted by Russ Kotlarek on May 15, 2008 at 01:13:32:

In Reply to: Re: hydraulic mystery solved posted by Tony Jurcan on May 04, 2008 at 12:40:58:

Fred, I also used the entire Lake style design for the hydraulic system including the Lake type valves, I have NEVER had a valve failure in the 16 years of flying my Lake nor have I heard of any to be honest. A superb track record... Parker p/n (8441E 1/4 D2P). Best Regards Russ