On Jul 15, 2:28 pm, wrote:

Well I guess that's the definitive answer. From now on it's DOT3 for my
bird's brakes, not that dangerous flammable stuff the spamcan drivers are
stuck with. The only potential downside I can see is water absorption,
which is more than handled by an annual flushing with a couple bucks'
worth of brake fluid.

And a few hundred bucks to fix the rubber bits. DOT-3 is a
vegetable-based fluid that is used with natural rubber. 5606 is a
mineral oil that is used with synthetic rubber. 5606 attacks natural
rubber, and DOT-3 attacks synthetic rubber. The flammability of 5606
is not an issue. I have no idea why anyone would risk trashing their
brakes and maybe the whole airplane when they either seize up or fail
altogether. The manufacturers of various vehicles specify certain
fluids for certain applications for very good reasons. A quart of 5606
would last the average owner about 10 years.
I spent 12 years building up and managing a machine shop that
rebuilt air brake equipment for trucks and earthmoving equipment and
hydraulic brake boosters for medium-duty trucks and some autos. We
made a LOT of money off people who put the wrong fluids in their brake
systems. We found motor oil (which is mineral oil) in systems designed
for DOT-3, and evidence of DOT-3 in air brake systems. Some of those
air brakes had alcohol injectors (for methyl hydrate) to prevent
freeze-up of the controls in cold weather (caused by condensation in
the compressed air) and guys would occasionally use anything handy
that had "alcohol" in it, like DOT-3 does. Wrong alcohol, though, and
boy, did it get expensive. The o-rings and other rubber bits would
swell and crumble and blow out and get into absolutely everything. If
you've had anything to do with modern air brake systems you'll realize
how extensive the damage can be. Those systems aren't simple.
Just drop some DOT-3 on your car's synthetic paint sometime and
see what happens.

Dan