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Thread: Best option for Sealed Struts

  1. #1

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    Best option for Sealed Struts

    I am looking for advice on purchasing sealed struts for a Super Cub. It looks like they are offered by or through Airframes Alaska, Aircraft Spruce, Univair, Wag-Aero, etc. Are there differences in terms of quality, strength, weight, etc? The main consideration is safety of course. Leaning toward the Airframes Alaska. Probably would not have them powder coated. The plane is operated in New England, some float operation, mostly grass strips. Any suggestions would be welcome. Thanks!

  2. #2
    skukum12's Avatar
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    I have had Univair sealed struts for 17 years now, been through many wind storms and snow loads in Alaska, no problems. Last I heard powdercoating sealed struts is not an option. There needs to be a hole drilled in the strut so it won't deform during the heating process, thereby eliminating the "sealed lifetime" quality of the strut.
    "Always looking up"

  3. #3

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    Not sure, but I believe Univair, not powder-coated, is the only way to terminate the entire AD. Be careful with the fork portion.

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    Last I knew Airframes rear struts can be powder coated without modifcation. Lots of guys drill relief holes in the front struts for pressure relief then refresh the tube oil and seal the hole with a set screw after powder coating.
    Last edited by stewartb; 05-04-2017 at 07:06 PM.

  5. #5
    mike mcs repair's Avatar
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    Airframe's struts COME powder coated if you want, ALL legal. and best choice.. ALSO STRONGER than Univairs.... but any sealed one is better than original style...

  6. #6

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    Those look nice. It says 5/8" forks front - no statement as to rear or as to magnaflux requirement. For a while the only struts without recurrent fork inspection were Univair. Also nice to see one can buy a new fuselage for ariund $12 grand.

  7. #7
    Steve Pierce's Avatar
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    Several choices. Univair struts are mild steel formed in dies like Piper did to shape. Not sure on Airframes but seem to remember them using 4130 streamline tubing. There is also a HD strut with a U channel welded on the inside like the Pacer and Tri-Pacer. Factory style struts work fine for flight loads but if you have heavy snow loads or heavy tail winds you might want stronger. I am sure a phone call to the folks at Airframes can clarify what they offer.
    Steve Pierce

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    I know the allure of the sealed struts to eliminate repetitive inspections but I associate sealed with Heavy Duty. The advantage of HD is to carry heavier snow and wind loads while tied down. Airframes struts that I've bought were HD. Are Univair struts also HD? Do they offer standard duty and HD? My BCSC kit included Univair struts and 5/8" forks. I never gave the HD thing any thought til now.

  9. #9
    Steve Pierce's Avatar
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    From Univair's catalog:
    Front Strut, Heavy Duty- Designed with stiffener channel welded in to help prevent wind and snow damage.
    Rear Strut, Heavy Duty- Designed with 4130 steel to help prevent strut failure due to wind and heavy snow loads. Includes heavy duty strut clamp.

    From Airframes website:
    These struts are best insurance one could have against snow load or wind damage. PA-18 Heavy Duty rear replacement lifetime sealed strut come with a 5/8" stainless steel fork and replacement jury strut clamp. Strut made from 4130 steel, roll-formed with .049 wall. New clamp is included to compensate for the slightly different teardrop profile on the heavy duty strut.
    Nothing on heavy duty front struts.

    About powder coating from Airframes website:
    Note: Struts cannot be powder coated once they leave our factory. Non-factory powder coating of a sealed strut destroys the preventative qualities of the oil inside and may distort the shape of the strut. Airframes Alaska is the only strut manufacturer with an FAA approved method for powder coating struts.
    Steve Pierce

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  10. #10

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    My Univair struts got relief holes drilled and were powder coated by Advanced Powder Coating like I described earlier. I wonder how Airframes does it? They didn't Powder coat the struts when I bought them for the -12 but that was 10 years ago.

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    Doesn't drilling and plugging automatically make you do the Maule test every two years?

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    Steve Pierce's Avatar
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    Stewart 's are experimental and Airframes has an approved process.
    Steve Pierce

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    n40ff's Avatar
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    Yea, I'd think drilling a hole for whatever reason would nullify "seal" and require inspection.
    Likes RaisedByWolves, Eddie Foy liked this post

  14. #14

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    Airframes' have a hole drilled in the top end of the strut which is welded closed after powder coat and epoxy primed. Any other "unsealing" and resealing of any sealed strut renders it unsealed in the FAA's opinion- the AD addresses this specifically. Not my opinion, theirs...

  15. #15

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    I understand the why for the regs but I'm not concerned in the least about drilling to powder coat and re-sealing my struts. Guys have been doing it for years. The difference is that I can talk about it because the FAA doesn't dictate what I can do anymore. Hallelujah!
    Thanks Yarddart thanked for this post

  16. #16

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    I appreciate the feedback! If I was going to go with Airframes, is there an advantage to powder coating versus buying them bare metal and having them painted? I know powder coating forms almost an enamel finish, but is it possible the process, whether approved or not, might slightly weaken the strut? I am not an engineer, so I don't know what impact heating the strut enough to melt the powder might have.

  17. #17
    mike mcs repair's Avatar
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    Powder coated is all I have used since it became available up here over 2 decades ago. And done by the same company they use, which does a much better job than others(prep, prime, coat)


    Sent from my iPhone using SuperCub.Org

  18. #18

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    Powder coating is probably the best reason to buy from Airframes. If I lived in the lower 48 and expected to paint I'd buy whichever was less expensive landed at my doorstep. Univair should have the freight advantage.

  19. #19

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    Does anyone know the weight difference between the original piper, Univair and Airframes struts? Per the website, the Airframes rear struts are 2.5 pounds heavier per side than the original piper struts. I think, but am not sure, that the Airframes front struts weigh the same as the original piper struts. Not positive on that.

  20. #20
    Marty57's Avatar
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    I contacted Univair in mid July about buying struts during planned trip to Airventure; I knew they offered a discount (I think 10%) at the show. I asked about shipping, pick-up at show, etc. I also asked if I could pick the struts up in Colorado on my way home but they told me they would have to charge tax. They quoted the shipping as less than Colorado sales tax so I had them ship to my house after the show. They gave me the Airventure discount over the phone (ten days before Airventure) and I didn't have to check in at Airventure or any other purchasing while there. Worked out great. If you can wait till before Airventure you can save a few $$$ that way.
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  21. #21

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    Univair has the weights. I wrote them down, but then filed them safely so I will only find them when I do not need them. I added six lbs going from unsealed J-3 struts to sealed PA-11 struts. All six lbs can be attributed to bigger forks and larger airfoil sections.
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  22. #22

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    I have a friend asking why not use Wag Aero sealed struts on J3?

  23. #23

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    Because you have to magnaflux the forks every 500 hours and replace them at something like 2,000 hours. With Univair, you install them and make a log entry terminating the entire AD.
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  24. #24

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    Thanks…I knew there was some good reason. I just couldn’t remember what it was.

  25. #25
    hotrod180's Avatar
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    One of the struts on a friend of mine's Pacer just failed the punch test.
    From what's I'm reading here, looks like Univair struts are the way to go?
    I'm talking more about not having to comply with any AD's, more than holding up parked under a snow load.
    Cessna Skywagon-- accept no substitute!

  26. #26
    Steve Pierce's Avatar
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    Pacer struts would be Univair or Airframes Alaska.
    Steve Pierce

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  27. #27
    hotrod180's Avatar
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    My friend is talking to AA about their aluminum pacer struts.
    Their website sez theyre not approved yet,
    but they told him via phone that they are now.
    They're about 2/3 more expensive (about $5K vs $3K),
    what are the advantages-- just weight?
    Cessna Skywagon-- accept no substitute!

  28. #28

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    Most guys I know use Airframes HD sealed struts and powder coat them. Rear struts can be coated as is. Front struts need to be drilled for a pressure release and then resealed. Not approved last I knew but it works fine. The rears are what fails first with snow and wind loads. HD are popular for that reason. For flight there’s no advantage.

    A friend added Airframes aluminum struts to his Maule to eliminate a repetitive inspection. I’m sure they saved some weight, too, but that wasn’t his priority.

  29. #29

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    This is probably a question for Airframes, but as far as I can tell, only Univair struts and forks get rid of that AD completely. The Airframes catalog lists the big forks, but down below it says that only parts specifically marked PMA or TSO (from memory -easy to look up) are eligible on certificated aircraft.

    So then I looked at their catalog, and the closest it comes to specifically marked parts is the occasional "replaces Piper part # . . .". What am I missing? I was looking for a statement that says "terminating action for AD . . ."

    Otherwise, it appears their pricing is competitive.

  30. #30

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    From the Airframes webpage-

    Airframes Alaska's Lifetime Struts satisy all current FAA Airworthiness Directives and do not require the recurrent inspections dictated by AD 99-01-05.
    Likes Steve Pierce, jrussl, bob turner, AZinAK liked this post

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