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Does anyone have any input on how one would acquire a landing gear strut spring? Apparently the springs are occasionally prone to becoming shorter than the required 6.73 inch “free” length. When this happens it causes that side of the plane’s wing to be lower than the other wingtip. A spring shortening of only 1/4 to 1/3 inch can make the wingtips several inches different. The plane operates and lands fine with the problem however it will look slightly different sitting on the ramp.
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Three choices:
(1) hunt for a used oleo and hope that it has a spring that still meets the dimensional and compression tolerance (or at least matches one you already have)
(2) get a new matched pair made. Many years ago, before I found a spare oleo to rob for parts, I looked into having some new coil springs made and the manufacturing shop I talked in Phoenix wouldn’t do a run of less than ten at a time for something like $2500 for the lot. The prices may have gone up considerably because that was 15 years ago. That said, with the proliferation of custom shops for off-road vehicles and motorcycles since then, maybe the price hasn’t changed too much. In any case, expense is a function of the time it takes to set-up the equipment, rolling the coil, grinding the ends to spec, plus heat-treating , shot-peening, and cadmium plating. Obviously there’s an economy of scale involved.
(3) get the ailing spring “reset” to the correct height. I have read differing opinions on the efficacy of getting the spring length reset, but the main issue is whether the L-5 oleo springs were hot or cold drawn, and I do not know the answer. I do know that only hot-rolled springs can be successfully reset and that the cost is on the order of 1/4 to 1/3 the price of having one custom made depending on the required finish. A little internet research suggests that in the automotive industry, SAE 6150 steel (from which our springs were made) is usually cold drawn, so resetting is probably not an option, leaving #1 or #2 as your choices.
Anybody else have input on this, please?
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I have a set of 108 oleo struts but have not taken them apart. The barrels are the same diameter but 1 inch shorter, and at full extension the same-diameter piston shafts are 1-3/4″ shorter. The 108 gear legs are shorter too and they swing through a smaller arc, so all of this suggests that the springs are also shorter. They might be stiffer in order to handle the same amount of weight, however, but all of this is guesswork so I’ll just have to disassemble one and find out.
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Steve Dennis hardly has anything. A year and a half ago I got pics of his meager inventory and bought a few parts. Most is in very poor condition or not L-5 except the frame and gear legs, and he did have a pair of oleos but I’d be surprised if they haven’t sold. It’s worth a call or email though. He’s in Rice Lake WI. Home 715-234-7613. Mobile 763-453-1378. Email: dennisaeroventures@yahoo.com or
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