Today's Message Index:
----------------------
1. 01:01 PM - Rim warning (Jeremy Casey)
2. 02:47 PM - Re: Rim warning (John Hauck)
3. 03:07 PM - Re: Rim warning ()
Message 1
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--> Kolb-List message posted by: "Jeremy Casey" <jrcasey@ldl.net>
As some of you know I bought a RANS S7 back last November. This plane
had MATCO MH6B rims that are manufactured by a "stamping" process. I
was told that there were some newer rims available that were heavier and
that are made by a CNC lathe process. There had been 2 RANS pilots in
the area that had had cracks in the older "stamped" rims (1 of which
came apart on landing...) I decided to put the new rims on my plane as
a just in case thing and to upgrade the brakes to the single
caliper/dual piston models for more stopping power. Anyway when I
pulled the old rims off 1 was cracked in 2 places and the other side was
cracked in 1!!! All the cracks where on the inside half of the rim
where it is hidden by the brake rotor. The rim with the worse cracks
would have been visible if it was taken off the axle (since you would
have to remove the rotor to do that) but the other one that was just
starting to crack WOULD NOT have been visible without splitting the rim
halves apart. All 3 cracks where at the ends of the "arms" of the hubs.
I assume there is some kind of stress riser there causing it. I am NOT
trying to bad mouth MATCO!! They make a great product for the
EXPERIMENTAL market at a great price. (IF they charged certified prices
they could afford to send replacement rims to everyone...but they didn't
;-) )
All that to say this...Pull those wheels off and look at them. If you
really want peace of mind, split them apart and inspect the inside...or
just sleep better at night and order the newer CNC machined rims. Mine
were the MH6B rims...the older stamped kind. Only took about 2 hours to
swap them out.
See picture here...
http://kilocharlieaero.homestead.com/files/crack.jpg
Jeremy Casey
BCD Drafting, Inc.
jrcasey@ldl.net
P.S. The S7 is probably 50-70 pounds heavier than a 912 Mark 3 which
might aggravate the issue but I wanted to pass this on to the Kolb-list
cause I know these rims are options on the Mark 3's and Slingshots...
Message 2
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--> Kolb-List message posted by: John Hauck <jhauck@elmore.rr.com>
Jeremy/Guys:
Thanks for the heads up on the ultralight wheel
problem.
In addition to cracking rim halves, the 5/8" ball
bearings are stressed to max when used on the MK
III, especially heavy ones like mine. The
bearings dry out quickly, rust and wear rapidly.
They should be checked frequently if you are using
them.
During my 2000 Alaska flight, my MK III was
equipped with these wheels. Had I not broken an
axle socket, the wheel bearings would have gotten
me a short ways down the road. When I got home
and pulled them apart, one or both sets of
bearings had already seized and the races were
turning on the axles.
Before the 2001 Alaska flight I upgraded to M62
wheels and brakes by Matco. They are 1185 lb
static instead of 600 lb, and use 3/4" axles and
tapered roller bearings instead of 5/8" axles and
ball bearings. Can be adjusted infinitely. Am
happy with these wheels and brakes.
Take care,
john h
Message 3
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--> Kolb-List message posted by: <rowedl@highstream.net>
Jeremy,
Thanks for the heads up. I have those wheels on my Mk-3 and will keep an
eye on them as the hours add up.
Can you tell us what size tires your Rans had on it, and also the emty
weight on your main wheels. Thought that each of these may have a large
influence on rim stresses. Also how much time was on the wheels?
Thanks again.
Denny
do not archive
----- Original Message -----
From: Jeremy Casey <jrcasey@ldl.net>
Subject: Kolb-List: Rim warning
> --> Kolb-List message posted by: "Jeremy Casey" <jrcasey@ldl.net>
>
> As some of you know I bought a RANS S7 back last November. This plane
> had MATCO MH6B rims that are manufactured by a "stamping" process. I
> was told that there were some newer rims available that were heavier and
> that are made by a CNC lathe process. There had been 2 RANS pilots in
> the area that had had cracks in the older "stamped" rims (1 of which
> came apart on landing...) I decided to put the new rims on my plane as
> a just in case thing and to upgrade the brakes to the single
> caliper/dual piston models for more stopping power. Anyway when I
> pulled the old rims off 1 was cracked in 2 places and the other side was
> cracked in 1!!! All the cracks where on the inside half of the rim
> where it is hidden by the brake rotor. The rim with the worse cracks
> would have been visible if it was taken off the axle (since you would
> have to remove the rotor to do that) but the other one that was just
> starting to crack WOULD NOT have been visible without splitting the rim
> halves apart. All 3 cracks where at the ends of the "arms" of the hubs.
> I assume there is some kind of stress riser there causing it. I am NOT
> trying to bad mouth MATCO!! They make a great product for the
> EXPERIMENTAL market at a great price. (IF they charged certified prices
> they could afford to send replacement rims to everyone...but they didn't
> ;-) )
>
> All that to say this...Pull those wheels off and look at them. If you
> really want peace of mind, split them apart and inspect the inside...or
> just sleep better at night and order the newer CNC machined rims. Mine
> were the MH6B rims...the older stamped kind. Only took about 2 hours to
> swap them out.
>
> See picture here...
>
> http://kilocharlieaero.homestead.com/files/crack.jpg
>
>
> Jeremy Casey
> BCD Drafting, Inc.
> jrcasey@ldl.net
>
> P.S. The S7 is probably 50-70 pounds heavier than a 912 Mark 3 which
> might aggravate the issue but I wanted to pass this on to the Kolb-list
> cause I know these rims are options on the Mark 3's and Slingshots...
>
>
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