Strut question?

How can you tell a strut that is mounted on an Cub if it's a sealed type or unsealed?
Thanks

Fork size is a good clue


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I would check the log books first. Some struts were modified with larger forks but this doesn't mean they are sealed. Look for a small screw at the top of the strut that would mean that they are not sealed but have had the SB done on them. Also look for the Univair stamp on one of the flat surfaces at the top of the strut. If this is a certified cub then there should be documentation for AD 15-08-04. The AD requires you remove the struts but some just do the maule punch test in place. I don't think this is a good idea. If you drill any holes in a sealed strut they are no longer sealed and require inspection as per the AD. I work on a Pacer that has 1 sealed strut and 3 modified with larger forks by F Attlee Dodge, so the AD is required on the 3 modified struts as they are not sealed. If in doubt you will need to remove the struts and check that the upper attach hole has a welded bushing and the fork end with fork removed to see if the hole goes into the strut tubing or not. New struts are not cheep but a failure could end badly. Most have been changed by now because the AD if done correctly is not cheep or easy to do every few years.

Just helped a friend/student pick up a Cub. I looked at the struts - old, small fork, no U stamp. I said "these don't look sealed to me." Seller said "yes, they are." Misrepresentation? Were there ever sealed struts with small forks that terminate the punch test?

bob turner said:

Just helped a friend/student pick up a Cub. I looked at the struts - old, small fork, no U stamp. I said "these don't look sealed to me." Seller said "yes, they are." Misrepresentation? Were there ever sealed struts with small forks that terminate the punch test?

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Yup ............. Wag still sells them. The 5/8-18 is extreme overkill when you compare its tensile strength with the 5/16 bolt in shear at the top attach. Everyone seems to get the "warm and fuzzy feeling" with the larger forks.

Southern Aero said:

Yup ............. Wag still sells them. The 5/8-18 is extreme overkill when you compare its tensile strength with the 5/16 bolt in shear at the top attach. Everyone seems to get the "warm and fuzzy feeling" with the larger forks.

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So I suppose you still have the 500 hour magnetic particle inspection on the strut and 2000 hr life?

Steve Pierce said:

So I suppose you still have the 500 hour magnetic particle inspection on the strut and 2000 hr life?

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Yes, couple months ago I removed the forks from a set of W-A struts and had them magnetic particle inspected. The owner of the lab wanted to feel warm and fuzzy about it so he also X-rayed them no charge. Dang it, they don't glow in the dark.

I think, pretty sure, that the shank size has more to do with being bent by ignoring the "no step" criterion for the struts than with the original tensile strength of the fork shank. If they get bent, then their in-service strength is an unknown.

Steve Pierce said:

So I suppose you still have the 500 hour magnetic particle inspection on the strut and 2000 hr life?

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Yeah I know......….. don't know why they still sell them, not much cheaper. Cost a lot more in the long run