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Anyone have an issue with bent gear legs?

Posted: Tue Dec 04, 2018 6:22 pm
by delaPlanet
Our DA40 XLS has the long gear legs installed. Our maintenance guys have noticed asymmetrical tire wear since the day this aircraft went into service back in October. They sent me a photo comparison of our DA40 with another one on the field and it's pretty obvious that the wheels are contacting the ground at the wrong angle. Apparently you can shim the gear/wheels to get +/- 2 degrees of camber, but that doesn't even look like it would get us close to a vertical wheel alignment. Do these gear legs look bent to anyone (see attached)?

I'm wondering if we adjust the wheel toe-in, maybe that would help "draw the legs back together" during forward rolling on the ground. Is that a crazy idea?

thanks everyone -

Re: Anyone have an issue with bent gear legs?

Posted: Tue Dec 04, 2018 8:52 pm
by Rich
Can't really tell from the pictures if it's unusually deformed. Certainly mine doesn't look like this. It has the "thin" (18mm) legs. Questions:

1. Is "the other" DA40 equipped with the same gear legs? There are three options available.
2. Are both sides of yours equally weird looking?
3. It kind of looks like maybe the wheel is off-kilter from the leg. Could it be wheel bearings or not-sufficiently tightened wheel retention piece? Axles off line or something?

Re: Anyone have an issue with bent gear legs?

Posted: Tue Dec 04, 2018 9:41 pm
by delaPlanet
Both wheels/legs are the same. I'm not sure which legs the other DA40 had on it. We are getting a strong push from our maintenance guys to replace the legs...but they're about $5000 for the pair.

Re: Anyone have an issue with bent gear legs?

Posted: Tue Dec 04, 2018 9:49 pm
by smoss
I have noticed the curve to most gear out there before. I have the "tall" ones.

Re: Anyone have an issue with bent gear legs?

Posted: Tue Dec 04, 2018 10:57 pm
by Rich
What does the gear look like with the plane up on jacks? Mine definitely shows that initial touchdown will be on the outer portions. But with the plane sitting normally on the hangar floor, empty except for whatever fuel is in the tanks, mine looks just like "the other one", with no detectable bend to the gear. Empty weight/CG would have some effect. Mine is 1705/95.53. Another factor could also be where the gear sits on the ground relative to CG, putting more or less weight on the mains as a result.

Re: Anyone have an issue with bent gear legs?

Posted: Wed Dec 05, 2018 12:30 am
by Rick
You can change the angle between the wheel and the gear leg much more than 2 degrees by rotating the shims, or installing them if you don't have them already. From your picture it looks to me like that is your problem, not a bent gear leg. My first DA40 had serious uneven tire wear - the inside edge of both tires wore to the cords before the outside edge showed any sign of wear - until my shop learned about the shims and how to adjust them. Once we got it dialed in, the tires both wore evenly after that.

There is a 6-year-old thread on this topic here with some tips on how to adjust the shims.

Re: Anyone have an issue with bent gear legs?

Posted: Wed Dec 05, 2018 7:15 am
by Karl
Asymmetric tyre wear is normal on aircraft equipped with spring steel gear legs.

The legs can often look a bit strange if the aircraft has been jacked up or turned tightly before stopping. It is best to roll it straight forwards a few meters before comparing the legs.

Re: Anyone have an issue with bent gear legs?

Posted: Wed Dec 05, 2018 7:11 pm
by Roxi5m9
Hogarth, I definitely second Rick’s comment. My mains were actually wearing on the OUTSIDE of the wheel as they were canted inward. The shims are cheap and a quick job for your mechanic. Start there for sure.

Re: Anyone have an issue with bent gear legs?

Posted: Thu Dec 13, 2018 11:04 pm
by delaPlanet
Yep - Our mechanic just did the entire measurement procedure. The main gear currently has no shims on it. He said that you can shim each wheel to a maximum, total correction of not more than 2 degrees. Unfortunately, the right main is 2 degrees off on camber and 0.5 degrees off on toe-in, and the left main is 3.2 degrees off in camber and 1 degree off in toe-in. This means we can't shim it back into spec :(

Re: Anyone have an issue with bent gear legs?

Posted: Fri Dec 14, 2018 1:54 am
by Rick
Hev you talked to Diamond yet? If not, call 519-457-4041 and ask them about the 2-degree max and see what they suggest. I thought you could even add another shim if needed to get the angle right. Diamond would certainly be the last word in what needs to be done to fix your misalignment.