Hydraulic & Brake Fluid

Rob58

Rob58

Moderator
I’m trying to get some confirmation on the correct fluids to use in a Cruisemaster. It seems the fluid designations have changed since the manuals were published. So we have: a) the hydraulic system (flaps & gear); b) the brake system, and c) the gear struts. Do we use the same MIL-5606 for everything? Are there different grades or preferred manufacturers of the fluids? What about the O-rings... do we need to match the O-ring material with the fluid type? Thanks, Rob
 
During the last 27 years I've owned my 14-19, all I've used is 5606 in the hydraulic system, brakes, and struts. Larry is correct in mentioning the composition of the seals. I've rebuilt each component and replaced hoses and seals over the years. All compatible with mineral oil. Tom Robinson
 
Thank you my friends - nothing better than the testimonials of those with experience. Really appreciate this forum! --Rob
 
I am sure Dan C will chime in on this, but I believe that 14-13 gear packing was actually Elk Hide, and that 5606 will turn those old seals into concrete. I dont know if 14-19s used the same seals, and I would assume most planes have had the seals replaced with modern synthetics, but sometimes original things are still on our old crates. Just something to think about. ____Grant.
 
Well...I don't know about the "elk hide".....Anyway, the "seals" on the 14-9, 14-12F3, 14-13, and 14-13-2 are all the same. The 14-13-3 and later Cruisemasters had a completely different shock strut that used "O" rings.
The seals [chevron packings] I have been using and providing to others seem to be made of a rubber/fabric material, like a fan belt. The early manual specifies "Lockheed #5," but I have used plain mineral oil in the struts. I also like to add "Granville strut seal" at the same time to keep the seals pliable. Otherwise, use 5606 everywhere else.
There are only a handful of pre-war Cruisairs out there and they used automotive based master cylinders whose kits probably were compatible with vegetable based fluids. The expander tubes of the brakes may or may not be compatible with this situation. So, I use DOT 5, silicone based fluid in this case because it doesn't seem to bother any type of rubber components.
Dan
 
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