Cleaning Hydraulic Filter in tank of 680FP

[ghancock]

I documented taking the filter apart and cleaning it tonight in my 680FP.  I found metal which I'll include in the post as well.

1) I removed the top portion of the tank with the center screw.  This doesn't come all the way out as it has a bar that tightens it against the lip of the tank and all you're doing is lossening it and swinging it around so that you can remove the top.





Once I got the top off I got a small plastic container and started scooping out the fluid in the tank and putting it back into the cans from which it came.  KEEP YOUR CANS :-)



Once I got enough fluid out to see the top screw in the filter, I reached down and started unscrewing it.  It is a nut that screws onto a threaded rod so it needs to come all the way off.



Here is the video of the entire assembly apart and shows how it goes back together.

http://youtu.be/BALmQaOJeeY

Here is what the sink looked like once I got through cleaning all the brass out of it.



Here are a few huge pieces I dug out of the bottom of the tank.



The fluid I removed was all still clean and purple despite it looking black when looking down into the tank.  I was actually surprised about this because it looks dirty from the top but was actually still very clean.

Anyway, the filter is a wire mesh and I cleaned it really good and then reinstalled it back into the tank.  I was surprised at how easy it was to do everything because I had been warned it was a really bad job.  Now I just need to figure out the direction of flow to see where else all that metal might have moved through before getting back to the tank. :-(

Glenn

[JimC]

How's your finger? 

"Skydrol fluids are irritating to human tissue. Gloves and goggles are recommended safety equipment when servicing Skydrol systems. If the fluid gets on the skin it creates an itchy, red rash with a burning sensation that just doesn't quit."

https://en.wikipedia.org/wiki/Skydrol

[ghancock]

I'm fine and yes I know.  The problem is gloves melt within minutes and you can't hold a single thing in your hands with them on.  The stuff doesn't bother me in the least and I'm careful to keep it out of my eyes.  I did try the gloves though but they are just too frustrating to deal with.

Glenn

[JimC]

I've never used it; I was just curious. Do nitrile gloves melt? If so, that would be some very scary stuff.

Horror stories about Skydrol were actually on the list of reasons I didn't get a 680FP and got the 340 instead.

[ghancock]

So I'm not saying it is awesome stuff to wipe all over you, but I am saying most people state fact from someone elses mouth and have never actually gotten involved in whatever they quote personally.  I heard the same stuff but have found that it isn't that bad as long as you make sure you don't get it in your mouth and eyes.  I've had it up to top side of my elbows and have never gotten rash or anything.  I do wash it off as quickly as I can once I'm done and sometimes will make multiple trips to the sink just to stay safe.

Glenn

[donv]

I used to dip my finger in it every preflight on the Jet Commander, and I never had a rash. In fact, I didn't know it could cause a rash. I was warned about not getting it on sensitive skin, however.

[ghancock]

I didn't realize the jet commanders used it.  I thought they were all bleed air?

Glenn

[donv]

The pressurization in the Jet Commander was bleed air, but the hydraulics were skydrol. If I remember correctly, hydraulics ran flaps, gear, brakes, spoilers, so nothing special.

I know they used skydrol at least through the Westwinds, and it wouldn't surprise me if the G150 still uses it.

If I had to guess, I would think maybe it's a part 25 certification requirement to have a flame-resistant hydraulic fluid.

[ghancock]

Cool, that would make sense and at least it wasn't getting pushed to 3000psi :-)

Glenn

[ghancock]

Just wanted to update the thread here and let everyone know that this cleaning and removal of all the brass from the filter has totally fixed my hydraulic flux problem.  It now sits at 3k and when turned on sits about 2900psi the entire time.  I can't believe that filter was causing the problem but Bill Leff suggested that it might be a situation where it couldn't get enough fluid to the pumps to keep the pressure up and that is what it was indeed.

So for the other 3 of you with these planes, it is a good idea to keep that filter cleaned. :-)

Glenn

[Willis]

Outstanding!

Thanks for the followup on this project.  I wouldn't have thought a filter THAT big would have caused the pumps to cavitate.  Hopefully there's no damage from it.

On to the next squawk. 
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Also, you should be rewarded for some fine project management.

kudos.

Bud