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<< Lancair Builders' Mail List >>
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Marv -
My Lancair 320 kit was purchased over ten years ago, so I have the older
Matco MC-1 brake cylinders. According to Matco, the MC-1 hasn't been
manufactured for over five years now, but they fully support rebuilding
existing ones. Although mine have been in service only two years, the
system has been filled for five years and the components sat on the shelf
for three years prior to that. After you start flying and as your cylinders
age, you'll become more conscious of possible brake failure, especially at
the wrong time.
Here is my recent experience for the benefit of all:
About three weeks ago, I started the engine for a local flight up
the coast. Before starting, I depressed the brakes and they felt solid.
During taxi out, however, one brake failed and "went to the floor". The
plane almost did a loop before I was able to stop the engine, that's how
critical differential braking is to steering. Still, that was a good time
for it to have happened, NOT during takeoff, landing or away from home.
Differential braking enables good steering of the plane and furthermore, it
cannot be operated without and braking failure at the wrong time could even
be fatal!
I ordered rebuild kits from Lancair, but they sent complete new
(MC-5) brake cylinders. I let them sit around awhile and then said "what the
heck, I'll install the new ones". Well, there was just enough design
difference that they wouldn't physically fit my older (MC-1) installation
without rework. So, I again contacted Lancair and this time received rebuild
kits for MC-1 cylinders.
There are the usual O-rings to replace. Then you'll find that the
actuating piston has to be removed from the stem. An extra small pair of
snap ring pliers is required. A glued-in rubber plug at the tip of the stem
seals a hole in the top of the piston....NOT a good design. Furthermore, the
plug's length is critical to proper sealing. (Matco is notorious for poor
designs, why do you think they've gone from the MC-1 to the MC-5 in ten
years?). When I found that the snap ring securing the piston was undersized
and wouldn't hold it securely on the stem, I called Matco and they
recommended returning them for rebuilding.
The worst part of all this is that I don't know how to predict
this type of brake failure. Maybe just automatically rebuild them after five
years or ????
Bill Rumburg
N403WR (Sonic bOOm)
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LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
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