Wheel bearings

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ahramin
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Wheel bearings

#1 Post by ahramin » Mon Oct 05, 2015 6:11 pm

How often should wheel bearings be repacked?
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Strega
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Re: Wheel bearings

#2 Post by Strega » Mon Oct 05, 2015 6:33 pm

I do mine every annual... doesnt take long.. and is cheap.. Dunno why they never put proper seals in wheel bearings on GA planes... would really make the bearing service much less..
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ahramin
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Re: Wheel bearings

#3 Post by ahramin » Mon Oct 05, 2015 6:35 pm

Yeah, mine are just felt. Like you say, it's free and bearings are $50 a pop.
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GyvAir
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Re: Wheel bearings

#4 Post by GyvAir » Tue Oct 06, 2015 7:46 am

There was another thread a few months back where you were asking about grease. As someone pointed out there, you can use one grease for everything, but for wheel bearings, especially if the plane sits outside not moving for longer than ideal periods of time, upgrading your wheel bearing grease to something like SHC 100 is a good idea. It does a better job of maintaining a continuous film (moisture barrier) over all the rollers and races than some of the greases called for in the old MMs. Not significantly more expensive either.
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Re: Wheel bearings

#5 Post by Hornblower » Sat Oct 17, 2015 5:00 am

To answer the question about how often, there are really two answers. 1. IAW the lubrication instructions recommended by the manufacturer, or 2. something more sensible depending on usage.

1. is actually the regulatory requirement if you are maintaining an OM or certified aircraft since you are probably doing the CAR 625 appendix B inspection; which states "Lubricate in accordance with the manufacturer's recommendations.". Unfortunatly most small aircraft lube instructions have you doing this annually, which is serious overkill if you are flying 50 hrs a year or thereabouts. Larger aircraft are often more sensible and have you doing the wheel brgs at tire changes. For a private owner there is probably something in between that is more sensible. If you are maintaining an amateur built, you are the manufacturer, and can set the lube schedule as you see fit.

I would do your little aircraft once at one year, and thereafter as you see fit. If you fly in seriously wet conditions, or in the desert you may want to do it more often, but in my experience wheel brg grease looks good even after 5 years or more if the utilization rate and operating conditions are benign.
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cgzro
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Re: Wheel bearings

#6 Post by cgzro » Sat Oct 17, 2015 5:23 am

More touch and goes means more wheel spinning, more bearing wear, more brake wear, more inspection of axles etc. required so more frequent greasing IMHO.

Anyway I do it every winter/annual simply because its easy, and I want to inspect the axles etc. anyway. Had a friend break an axle with disastrous consequences (write off an expensive tail dragger) so I like to clean / inspect the axles / bearings / bearing surfaces every year.
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Re: Wheel bearings

#7 Post by Hornblower » Sat Oct 17, 2015 5:55 am

Ya, I get that, but in a flying school where they do circuits all day, ... tire change intervals work fine, so no private owner would have that usage. In most case it would be the age of the grease, or water ingestion, and I've seen five and ten year old aeroshell 5 that is just fine. So like I said, figure out what works for you. As for the axle breakage, greasing wheel brgs won't affect that; and inpecting axles ... you are not likely going to see anything with your naked eye that would indicate impending axle failure. So I think you are busying yourself to make yourself feel more confident, however I think it is pretty well a psycolgical issue.

Good to see you up early this fine day, going out to get some pitts x-wind practice at YND this morning?
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Re: Wheel bearings

#8 Post by NunavutPA-12 » Sat Oct 17, 2015 6:35 am

My wheels (wheel-skis) are only on the 'plane in cold weather. I don't usually fly below -20C, but should I be using some kind of low-temperature grease for the wheel bearings? Amateur-built.
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Re: Wheel bearings

#9 Post by cgzro » Sat Oct 17, 2015 5:55 pm

you are not likely going to see anything with your naked eye that would indicate impending axle failure. So I think you are busying yourself to make yourself feel more confident, however I think it is pretty well a psycolgical issue.

Good to see you up early this fine day, going out to get some pitts x-wind practice at YND this morning?
Probably right but the winters are long and I have have to check the plane for cracks pretty carefully anyway. Aerobatics is pretty hard on a plane so I have magnifying glasses and polishing stuff. I have found a few over the years in my and other people's aircraft.

No Pitts-ing today, sadly she's down for a broken tail brace that will need some welding and fabric repair so be a few weeks I suspect. Today had a friend's Chipmunk up a few times to check out the fall colours. Great little plane in the 15G20 cross winds. Even had some snow showers .. grrrr.
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