Looks like someone pushed up on it. Did that to the upper end of one, pushing up towards the top of the strut trying to get my tire unstunk on a sand bar.
I see nothing structurally wrong with it as is. All the loads are in tension. Just looks bad. I suppose you could weld a piece of welding rod in the middle and then heat the whole thing up with a torch while pulling on the rod. Would that cause an issue on a sealed strut?
Metal tubing can fail under compression. A misspent youth taught that an adult beverage can be hard to stomp flat unless a side dent was first formed. I had a strut with an external "sleeve repair" welded per AC 43 on my Taylorcraft.....we replaced the strut.
Did you ever look at a G-meter after one of these events? You would be surprised that under most situations it's never less than zero. The only time I've seen a high negative number was in a boat seaplane (Colonial C-1 or Lake) in extremely rough water.
In one -G event in a 7ECA I had a pencil, chart, and dirt floating at eye level for a brief period. Reminded me that wood spars were flexible yet strong when we hit hard bottom. Downwind rotor clouds to be avoided apparently.
Only slightly negative, not -1 g required for that. I'm not an A&P, but I'd be a little leery. Maybe the manufacturer publishes a dent limit?? Seems 43.13 has dent limits and repair methods.
Not A&P, but From AC 43.13-1B CHG 1 Par 4-94, a. Dented Tubing. (1) Dents are not deeper than 1/10 of tube diameter, do not involve more than 1/4 of the tube circumference, and are not longer than tube diameter.