Lift strut questions

[pistoncan]

This may sound like a dumb question, but Ive asked them before and other people have said they wondered too, but didn;t want to sound dumb. (I don;t mind) What is the difference between sealed struts and standard struts? and before someone says "they are sealed" I have a standard strut and it sure looks sealed to me. Is there supposed to be a drain hole or something in them? Are the sealed struts filled with some ineret gas? Inquiring minds wnat to know G

[Steve Pierce]

Sealed struts have a bushing welded at the top of the strut where the bolt goes that attaches the strut to the wing. Also the bushing that the lower fork screws into is not opened into the strut but capped. They are filled with an inert gas and welded shut. No dumb questions Gary. I asked this same question years ago. :lol:

[Stephen]

No drilled drain hole in the standard strut either. Just need to check them according to the AD.

[Glen Geller]

A few of the hints about Piper struts:
* Original struts require an elaborate inpection every two years involving a Maule punch and adding anti-corrosion oil. A pain in both the ass and the hands used to operate the punch. Fun Fact: If you have a mechanic do this inspection, in ten years you have probably paid him the equivolant of new struts and still have potentially dangerous old struts.
* If your struts have door catches screwed into them, they are not sealed (not anymore, anyway!)
Owners with sealed struts usually fabricate a cuff with the door catch riveted on, the cuff then clamps to the strut.
Same for the upper strut cuffs, they cannot screw thru the wall of the strut or it is no longer sealed.
* The original struts have 7/16" threaded lower strut forks. Inspect for cracks at annual.
The sealed strut have beefier 5/8" threaded strut forks (these won't fit with "original" struts, gotta replace the whole shebang)
* You cannot buy the "original' style struts and forks new anymore, only the sealed/HD versions are available (Univair, etc)
* The new struts and forks have repetitive inspections as well but they are much less frequent and much less painful.

[Steve Pierce]

I was told today that there is no inert gas in the struts, just welded shut. No air and moisture going in should make them lifetime, at least ours. ;)

[Glen Geller]

I may be mistaken, but aren't the sealed struts partially filled with anti corrosion oil before they are welded shut, to keep the lower part of the struts oil-saturated and a generally oily atmosphere inside the strut?
GG

[Steve Pierce]

I doubt there is any oil put in them. The tubing has oil on it. I would think the oil in a sealed strut would gas and blow out the weld when sealing the strut

[Hillbilly]

I doubt there is any oil put in them. The tubing has oil on it. I would think the oil in a sealed strut would gas and blow out the weld when sealing the strut


Surely if the oil is put in carefully (not splashed on the weld area) and the strut remained upright it would not even get warm.
Univairs ad for sealed struts says; "New Oiled and Sealed Lift Struts". - Hillbilly

[Glen Geller]

I think a strut that's around six feet long can had a pint or two of airomatic oil and still be only ~20% full.
Inverted and welding at the 'top end' to secure the lower fork nut would not likely heat up the strut much at all.
The old welding trick of wrapping a cool damp towel around the other end would keep things cool.

[Steve Pierce]

As many Univair struts as I have put in I have never felt anything rolling around in them. I have cut a few bent ones apart and they were oily inside but no accumulation of oil in the bottom. Even when welding on a fuselage the heating of the tube expands the air inside and wants it to blow out the weld. We usually have a vent somewhere and it gets welded up quickly when all the heavy welding is done.

[Hillbilly]

According to Univair:

The struts are manufactured in house by us.
The oil used is called Val Oil.
The front struts have 6oz, rears have 4oz.
Thank you for your inquiry.
Regards, Rick

-Hillbilly

[pa20]

I bit the bullet a few years ago, and installed the sealed struts. Since then I have been flying the plane without the upper cuffs as I have not been around enough to sort out a method for attaching them at the strut/wing interface.
I would like to hear from others about the methodology that has been employed to attach the cuffs. I have been thinking of wraping the area of the strut where the lower part of the cuff would be with a thin silicone rubber to provide a friction surface, and then manufacturing small tabs that would tighten the cuff around the strut. That however does not secure the cuff at the top.
Pictures would be great!
Thanks

[d.grimm]

I used a L-shaped aluminum strap with a nutplate riveted on, One under the bolt head and one under the nut.
Then I cut a 1/4 in strip of velcro for the perimeter of the bottom edge. Has held up fine for 6 years.
Dave

I have an friend that recently imported a PA 22/160 from South America. Homer Landreth handled the FAA Paperwork. The aircraft had sealed lift struts installed in place of the front struts but left the origional rear struts in place. I didn't see any notation in the logs for inspection on the rear struts per the AD. We flew the Aircraft to OshKosh from Arizona and I spent more than a few minutes looking out the window at those rear struts.

The Aircraft has been through 2 annual inspections since arriving in the USA. I wonder what the consensus is on this? This is a $1000 question.

Mark Phillips

[Steve Pierce]

Here is the AD. Sounds like you need to check when the forks were last magnafluxed (500 hrs.) and punch test every two years.
[attachment=0:2k3z3j1d]AD 99-01-05.pdf[/attachment:2k3z3j1d]

[rsmith]

New guy here with a question about forks. I've got old unsealed struts. The forks look a lot newer than the struts, so I assume they've been replaced at some point (though I can't find anything about it in the logbook). What bugs me is that looking at the threads, they look sharp, like cut threads to me. My old eyes may be fooling me again, but can anyone tell me a way to tell the cut threads from rolled threads?

[walt.buskey]

Can't answer your question, but when faced with the same situation I opted to bite the bullet and replace all struts, doing away with the %$$# 2-year AD. New, 5/8" stainless forks came with the new sealed struts so I just replaced everything. Got mine from Airframes Alaska, even got them to powder-coat with white paint to match.

13194

[tnowak]

I seem to recall that if you look at the threads with a magnifying glass you can see the difference.
Cut threads look rougher than rolled threads.
TonyN

[Steve Pierce]

Yep, what Tony said. Did you check the AD compliance list to see if anything was noted there?

[rsmith]

Thanks for the input. Once I got them under some magnification with good light, I could see they were rolled threads.