Sticky struts on Piper

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Danny Dub

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Danny Dub
I know it is kinda normal but is there anything that sticky struts indicates? Sometimes the things go down to within 1 inch of bottoming out and other times they stay 8 inches extended. Or anywhere in between.

Kind of annoying when the plane sits in a 15 degree bank on the ramp!

Is there anything what can be done?

1966 Pa32-260



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Danny Dub said:
but is there anything that sticky struts indicates?
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When was the last time the strut fluid level was checked or the fluid changed? Sometimes if the fluid level is low but serviced with the correct air pressure it can cause them to stick. Same if your struts are dirty. Try wiping the struts with 5606 on a regular basis and see if that helps or check/replace the fluid which is considered prevent mx if you're interested in doing the work yourself. Procedure should be in the POH or if not in a service manual.
 
Thanks that's great advice I'll look into that.

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There is a product called “ Strut Wipe” that is a cloth saturated with 5606.

Reviews note it as convenient. Owner is active on Piper Forum or google.

“Bend over and wipe”!
 
Magman said:
There is a product called “ Strut Wipe” that is a cloth saturated with 5606.

Reviews note it as convenient. Owner is active on Piper Forum or google.

“Bend over and wipe”!
Click to expand...
He’s here too. @Strutwipe
 
Maybe he can comment on advantages.
 
Bell206 said:
When was the last time the strut fluid level was checked or the fluid changed? Sometimes if the fluid level is low but serviced with the correct air pressure it can cause them to stick. Same if your struts are dirty. Try wiping the struts with 5606 on a regular basis and see if that helps or check/replace the fluid which is considered prevent mx if you're interested in doing the work yourself. Procedure should be in the POH or if not in a service manual.
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Can 5606 start to get thick when it get's old?
 
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It can get nasty looking. Not sure how old is old though. I’ll guess small amounts of crud get by scrapers and o-rings.
 
Gary Ward said:
Can 5606 start to get thick when it get's old?
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As mentioned above when exposed to the air it will. When its in the strut or stored not really. What mainly happens in the strut is it gets contaminated and turns into a black, stinky, liquid shieet over time. On storage, there is a shelf life like most things but depending on brand and if stored properly have seen it go years with no issues. But at some point part of the additives start to degrade and it may not meet its spec no longer. Then again I never keep 5606 that long. However, I have removed quite a bit of black, stinky liquid over the years that was probably well past its useful life. There are a few people out there who think only nitrogen goes in a strut.;)
 
What do you guys think about using mineral spirits to clean the bugs and grass off the strut chrome shaft on a regular basis?
Think that would help the OP any?
It cuts the sticky 5606 and seems to provide the proper lube for the seals?
Now if I didn't fly much then I would be a little concerned with rust on the shaft if it sit's a lot after using MS. Then maybe light lube instead of 5606?

In the McFarland printed catalog they recommend mineral spirts to clean the strut chrome, I could not find that same recommendation online.
What do you think?
 
Gary Ward said:
What do you guys think about using mineral spirits to clean the bugs and grass off the strut chrome shaft on a regular basis?
Think that would help the OP any?
It cuts the sticky 5606 and seems to provide the proper lube for the seals?
Now if I didn't fly much then I would be a little concerned with rust on the shaft if it sit's a lot after using MS. Then maybe light lube instead of 5606?

In the McFarland printed catalog they recommend mineral spirts to clean the strut chrome, I could not find that same recommendation online.
What do you think?
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The solvent would work far better at cleaning the strut. It evaporates and leaves little residue. Even better would be brake cleaner, the non-chlorinated variety.

If a strut barrel rusts, its thin layer of hard chrome is shot and the barrel needs replacing. The chrome gets nicked by debris thrown up by the prop and nosewheel tire.

Stickiness can be due to deteriorated fluid that has lost its lubricity, or to aged-out seals in the strut. The seals are Buna-N, an old synthetic rubber from WW2. That stuff degrades and hardens and sometimes softens with age. That's one reason the fluid turns that ugly black. Another reason for black fluid is corrosion inside the cylinder caused by using air, which always contains at least a bit of moisture, sometimes a lot of it. That strut should come off and come apart and get cleaned out and new seals put in, and it should be fine for some time as long as the cylinder isn't all corroded so that the upper end is catching on the pitted surface. Or a pitted barrel is sticking in the seals.

Old airplanes are so much fun...
 
Gary Ward said:
What do you guys think about using mineral spirits to clean the bugs and grass off the strut chrome shaft on a regular basis?
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40+ years ago it was beat in my head to use 5606 to wipe struts on aircraft serviced with 5606. I 've never detoured from this "advice". However, I have seen and replaced strut seals where a different chemical was used. In my opinion 5606 is a great cleaner and readily available. As a side note there are newer hyd fluids that are a direct replacement and compatible to 5606: MIL-PRF-83282 or -87257 which provide their own improvements.
 
I live in a dry, very dusty climate. When my plane was parked outside, I had sticky struts all the time. Ever since I moved into a hangar, sticky struts no more.
 
Thanks all for the replys and suggestions. All good stuff. I'm gonna look through the logs to see when the last time some love was given to the struts. May be time for at a minimum a fluid change and also maybe seal replacement. Notably they dont leak down really so does that mean seals are probably ok?

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Danny Dub said:
Thanks all for the replys and suggestions. All good stuff. I'm gonna look through the logs to see when the last time some love was given to the struts. May be time for at a minimum a fluid change and also maybe seal replacement. Notably they dont leak down really so does that mean seals are probably ok?

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The seals can hold but still be hardened or permanently deformed. Old seals used to reveal themselves to us northerners on the first really cold day. They'd either shrink just enough to pull away from the O-ring groove bottom and let the fluid and gas seep out, or they'd shrink and grab the barrel and get spun when the strut compressed and get a spiral fracture, losing all the stuff at once.

It really bugs me that there are much newer, far superior O-ring compounds that would last far longer, seal better, and not be grabby, but the OEMs still list the MS28775 Buna rings in their parts manuals. From the '96 and on 172 parts catalog:

upload_2022-10-28_12-10-2.png

They upgraded fuel system O-rings to fluorocarbon or fluorosilicone. I wish I knew why they stuck with 1940's technology for the strut.
 
Dan Thomas said:
They upgraded fuel system O-rings to fluorocarbon or fluorosilicone. I wish I knew why they stuck with 1940's technology for the strut.
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It actually extends into all hydraulic type systems. There's compatibility issues with that seal material and most hydraulic/brake fluids, various ketones, etc. They've tried for years to find better hyd seals for helicopter hydraulic servos, etc. but none lasted as long as the nitrile material.
 
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Dan Thomas said:
The seals can hold but still be hardened or permanently deformed. Old seals used to reveal themselves to us northerners on the first really cold day. They'd either shrink just enough to pull away from the O-ring groove bottom and let the fluid and gas seep out, or they'd shrink and grab the barrel and get spun when the strut compressed and get a spiral fracture, losing all the stuff at once.
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Did Granville Strut Seal address the issue?
 
Domenick said:
Did Granville Strut Seal address the issue?
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FYI: you'll find Granville is nothing more than MIL-H-83282 synthetic hydraulic fluid which is an alternate to the oil based 5606 and bought in the same stores. The synthetic fluid reacts differently with the seals and improves their sealing ability.
 
Dan Thomas said:
I think it just swells the rubber to keep old seals going for awhile.
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Its my understanding the synthetic fluid compound found in Granville and MIL-H-83282 "bonds" to the nitrile seals and keeps them wet vs swells them. Lot of different ops used Granville until they converted over to 83282 fluid. Cheap fix in some cases except for bitter cold areas as 83282 doesn't have the cold temp performance as 5606.
 
Bell -Thanks. Never knew what it is.

I’ve used it for many years to address leaks, not stickiness. Not a 100% rate but may be worth a try.

I should have tracked how long it was before a tear down was needed. A 182 nose strut and and Commander 114 main “ shock” are 6 years and counting.

It is NOT an instantaneous process. After introducing into the unit ; best results are achieved if you allow a few days for the reaction.

There are folks here that use in their biz- jets. They say Iceland is not ideal
to replace strut seals.

It’s rather common for Cessna nose struts to collapse at the first cold snap. The issue is the o-ring in the top of the strut. Keeping Granville in the strut seems to
help. I’ve had some success putting it in the “well” at the top where it can wick down and possibly soften the seal.

Columbus took a chance!

I would say the ideal time to wipe down struts would before flight. That way there is less chance of grit sticking and getting past the scraper.
 
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