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Bungee struts needed

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Paul Smith

Guest
Hey guys,

When I bought my L-4, it came with a strange pair of shock absorber struts instead of the bungee struts. I want to get it back to normal. Would anybody happen to know of a set that is available? Much Grass!

Paul
 

longwinglover

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Univair has them in stock.

Why would you risk your L4 on an unknown set of landing gear components?

John Scott
 
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Paul Smith

Guest
Hi John,

They're not really unknown. They've been on the airplane since the 50's. It's just that I've never seen a Cub with shock absorbers on the gear instead of bungees. Strange! I don't like them at all because they pull the V's together and she sits up too high. Plus they're just not correct.

I know Univair has them, I'm just cheap!

paul
 

longwinglover

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Paul,

I re-read my post and I apologise if I was a) a bit short/flip and b) not clear in my answer.

The "unknown" part of my post was in reference to used landing gear components you might get from some other party, not the one's on your plane. Parts can come from a lot of sources, but in my opinion a lot of parts become available because they have been replaced with new. If it was questionable to or not good enough for the previous owner, why is it good enough to trust on your plane?

Of course Univair is expensive but they are the best supplier of PMA'd parts for the Cub. We all want to convince ourselves that owning and flying a Cub is cheap and the operations are - until we have to start buying quality parts. The point I was trying to make was that I think it may be a false economy if we replace a part with used/unknown when new is available. One may save several hundred dollars on the used parts, but if they fail, the damage resulting will be significantly more expensive than the dollars saved.

I am curious about the origin of the parts you are replacing. Can you determine from the paperwork who the manufacturer is? It would be interesting to know of a certified alternative to the bungees (excluding the AOSS system). If the springs in your system are pulling the gear in and making the Cub sit too high, the overall length may be too short. Original shock struts with new bungees will pull the gear in to the stops, but not too much.

Sorry for any confusion I caused with my original post.

John Scott
 
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Paul Smith

Guest
Hey, Negative persperation there, John.

I really don't know where they came from, except to have heard from Dave Henderson that he's restored several other L-4s from Switzerland and has seen the same struts several times. I am well aware of penny wise-dollar foolish economy with parts, especially gear parts, so I'm going to do extensive taxi tests before I try landing the airplane on them. If I decide to sell another gun, I might be able to buy them before the rest of the airplane is done, anyway. I can't determine anything from the logs as Zey are all in Sviss Cherman!

You and I are on the same page anyway, as I would have any second-hand parts magnafluxed before I installed them.

Thanks
 

longwinglover

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Paul,

Thanks for the update on the springs. I've heard of the European modification replacing the bungee system.

John Scott
 
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Paul Smith

Guest
Hey,

The airplane hasn't had an annual in it's life! It's never been signed off. The reason for this is because the last time the airplane flew in the US was when they flew it from Lock Haven to Newark in June of 1944! it has been towing gliders in Switzerland since the end of the war.

We're just on the last stages of a frame up restoration. I intend to apply for a 337 approval for now, and replace them with correct struts later.

Paul
 

will767

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John T,
Several weeks ago there was a string of postings about the future availability of bungees. I don't know if the concern expressed in those postings was rumor or real.
If indeed these units will be extinct some time in the future, all cubs will have to be retrofitted to some other design.

On the other hand if the availability of bungees is not threatened, then to maintain originality, buying a new set of struts from Univair is what I'd do.

Paul,
If you want to use the shock absorber struts you have, it seems you are dealing with two problems.
(1) you want the plane to stand correctly. (2) you have to get the installation approved.

(1) Chances are the struts you have were made for an earlier model airframe, they were slightly narrower than the later models. To make them work for you, the attaching area on your vee will need to be extended.
Remove the welded on plates from the vee make new ones from the exact thickness of the originals and from 4130 steel. The extra distance between the bolt holes you will have determined is what is needed to stand the plane correctly. weld your new plates on the vee.

(2) Getting a "One Time Field Approval" in my opinion would be the way to handle the legal stuff.
The mod on the Vee and the strut installation could be part of the same approval.

FIELD APPROVALS arn't that to hard to do, However I'd run it past your AI and maybe the local FSDO engineer before starting on the conversion. Jim Swayze

 

reileyr

WagAero J-3
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Sounds like your L-4 may be equipped with PA-18 hydrosorb shock units. Hard to tell without a picture or part number. Hydrosorbs were optional on PA-18's. There may be part numbers stamped on the unit. If not, a PA-18 parts manual will have numbers and a crude drawing.
 
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Paul Smith

Guest
Hydro-sorb, Huh?

Never hoid of 'em!

Anyway, that may be a way of getting them approved. Many thanks. I am just interested in getting the airplane in the air at this point, and I don't want to keep the shocks on it, as they just aren't historically correct for the airplane. I need to get a set of bungee struts at some point, but can't swing $800 for Univair right now with all the other stuff I have to do on it. I am holding for a tach with a 45* fitting, and final plumbing of the fuel tank. A guy in the hangar across the way says he may have an original fuel shutoff valve for me. If he does, I can get rid of Rube Goldberg's (Univair's) replacement fuel valve and get the tank sealed up and ready to go. Then I can get a DAR.

Thanks again fellows...

Paul
 

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