Earlier, Ventus B wrote:

The maintenance manual for my ASW 20C glider
says to be sure to only use 'mineral oil' based
brake fluid for the hydraulic brake system.

MIL-5606 is pretty much the standard mineral-based
hydraulic fluid for aircraft applications. It costs
about $6/quart from Aircraft Spruce:

http://www.aircraftspruce.com/menus/...omponents.html

As far as I can tell, DOT 3 and DOT 4 brake fluids
are glycol based, and DOT 5 is silicone based
according to my 15 minutes of research on
the internet. The problem is, I still can't tell
if any
of these meet Schleicher's admonition to only use
mineral oil based brake fluid. I would suspect
that of the three, that the DOT 5 silicone based
fluid appears to be the right one. Can anyone
corroborate this? Anybody know the 'right'
answer?

When I cobbled together a brake system for my HP-18
using Yamaha and Cleveland brake parts, I decided to
use a silicone brake fluid as well. It was the only
thing I knew (from experience) to be compatible with
both the DOT 3-compatible seals of the master cylinder
and the MIL 5606-compatible seals in the caliper.

Getting slightly off-topic, I'm betting that we're
T-minus a few minutes to a cap-locked post about how
silicone should never be allowed with 50 meters of
a composite strucure, or else it will never be repairable.
I've heard plenty of folks say that, but I have not
seen any substantiation in any of the composite glider
repair manuals I've read.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24