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LR,
I'm just speculating here, but the spring steel gear was a factory option on the Alon A2. If it was a factory option, I would think that an A&P could remove the old gear, install the new, and just sign it off with a 337. The weight and balance form would have to be updated, because the spring gear is reportedly lighter than the original gear. I understand that one of the lady Alon owners did the opposite a few years ago - replaced the spring gear with trailing link gear, so if you could find out who that was, maybe you could go the same route as far as paperwork goes.
As far as I know, the bolt hole pattern is the same on both types of gear legs, so bolting them on should not be a problem. I would use all new hardware when mounting the gear legs. The bolts are special NAS146-35 internal wrenching socket head type bolts (new P/N is MS20006-22). When I removed mine, the bolts didn't look too bad, but they did have some light rust on them and showed some signs of wear. If you need a source for them, let me know and I'll look up where I bought mine from. I think that they were about $45.00 for the six of them. (John at Skyport could probably supply them.) Also, when you install the gear legs, note that there are not supposed to be any washers under the bolt heads. The washers go under the nuts. These bolt heads have a small radius between the shoulder of the bolt head and the shank of the bolt. The gear legs have a beveled edge cut into the bolt holes. The radius on the bolt fits into the bevel on the gear leg hole. Putting a washer under the bolt head will not allow the bolt to seat properly. (There are special washers available to use under the heads of these type bolts, but none are supposed to be installed for this application.)
A few weeks ago I talked to a guy from PA who has an Alon two serial numbers earlier than mine, and he had a gear leg fall off the plane after landing because the bolts cracked and broke. I don't know how this could happen short of crash landing the plane, but he said that's what happened to his. He said the bolts were cracked and had signs of being cracked for a while prior to the incident. Luckily the plane had only minimal damage. He said that he had noticed some unexplained vibration on a few landings before the failure.
A while back, I bought a set of the spring steel gear legs off of E-Bay, and when they arrived I immediately saw that they were bent. One of them had a single bolt stuck in a bolt hole, and that bolt was sheared off from a crash landing. I returned these legs to the seller, and he said that he was going to have them fixed by a certified shop, or if they couldn't fix them he was going to destroy them. I would have felt better about it if I knew that they were destroyed, but I don't know what happened to them. Buyer beware!
If you are thinking about putting spring steel gear on your plane, it might be a good idea to have the gear legs magnaflux inspected before installing them. I have heard of two gear legs breaking due to cracks in the steel. (One was the lady owner that I mentioned above.)When I rebuilt my plane, I took the gear legs to a local inspection lab and had them magnafluxed. I explained to the shop manager that I didn't need any official paperwork on the inspection, but that I just wanted to make sure that they weren't cracked. Because there was no liability and no paperwork involved, they did both legs for me for $80.00 while I watched. Money well spent, considering the possible results of a broken gear leg.
A couple of other opinions - While I prefer the spring steel gear over the original gear, I personally do not think that the spring steel gear legs are quite as rugged as the original type gear legs. I don't think that they will withstand the same level of side loading abuse as the originals will. They are however, lighter in weight, almost zero maintenance, and I think they look better. Also they don't have issues with parts wearing and causing the tail to droop. I'm not sure that I would want a set of spring steel gear legs on an Alon without the rudder pedals. I'm always extremely careful with my plane not to touch down unless I'm lined up straight down the runway and not drifting to the side.
Another thing to look at is the condition of the metal between the axle attachment fitting and the gear leg. The axle is held on with a machined metal block that attaches to the gear leg with six bolts. On one set of spring steel gear legs that I took apart, the block had started to corrode where it was bolted to the gear leg. The corrosion cleaned up OK, but if left alone, it would have gotten progressively worse and might have caused a failure 100 years down the road (gotta plan ahead, you know).
And finally, below is a link to a posting from the guy who evidently designed these gear legs for Alon. It is pretty interesting reading, if you are interested in these gear legs. He mentions that the shock absorbing action (as opposed to the spring action) of the gear leg is provided by allowing the gear leg to twist upon impact, and the shock absorbing is due to the tire "scrubbing" on the pavement when the gear leg twists. This is why the bottom portion of the gear leg is so thin compared to the top portion - so that it can twist. I thought that this was a pretty good example of why one should not assume that one knows all about something on the plane just because he has looked at it and studied it. I could have studied these gear legs for 10 years and never realized how these gear legs really work! That's sort of scary in a way.
Let me know if you want any digital pictures of the fittings, bolts, gear legs, attach points, etc.
As always, all of this is just my opinion, so check with your licensed mechanic before using any of this info.
Best Regards,
Wayne DelRossi
Alon N5618F
Hours logged since restoration: 114.0
Wayne DelRossi
Alon N5618F
Hours logged since restoration: 114.0
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