Grove Brake Fluid

[sonex892.]

What would your recommendation/suggestions be??Aircraft located in Australia

Here is on in Oz. Spec sheet says this is 5606. https://www.e.com.au/product/aeroshell-fluid-41/

[Skippydiesel]

My last air craft an ATEC Zephyr powered by a Rotax 912 ULS, used very few "aviation components" in its compost/wood/fabric construction. All fasteners were of the shelf metric - high tensile & stainless steel where applicable. Brake fluid, ordinary automotive (changed every 2 years). Very nice aircraft with impeccable flying characteristics and extraordinarily cheap to run (13L/hr at 100 knots, capable of up to 120 knot cruise and a 30 knot stall).
Dedicated aviation parts/materials have their place but to suggest that nothing else will do, is just plain wrong - dont forget your Wright Brothers did not use certified aviation materials in their aircraft and look what they achieved.
Recreational aircraft do not need high cost dedicated aviation materials. As for brake systems, there is absolutely no good reason why the manufactures of aircraft brake systems (for recreation level aircraft) could not use automotive fluid compatible seals (they do in Europe).

[Area 51%]

A problem with older (time in service) Automotive fluid is that it has absorbed quite a bit of water into its molecular structure. It is thus prone to freezing at altitude.

Agreed.....most automotive brake fluids have a great affinity for water. I ain't buying the freezing at altitude, though. Unless -10F is different at 10,000ft than it is in a Michigan driveway in Feburary.

Automotive brake system reservoirs are not vented directly to the atmosphere, but have an accordion-like seal to take up space without allowing moisture laden air to contaminate the fluid. Given that some H2O is going to get into the system, regardless of the care taken, there must be some allowable percentage. That information is probably archived along with the Dead Sea Scrolls and Ten Commandments.
As a matter of fact, engine coolant's freezing point goes DOWN with the introduction of water. To a certain point. Does brake fluid possibly exhibit the same characteristic? Any articles I've read on moisture contaminated brake fluid revolves around corrosion. Never seen a reference to "frozen fluid".

Having said all that.........my Sonex supplied master cylinder had a sticker on it reading "DOT 5 fluid only".

[Scott Todd]

"my Sonex supplied master cylinder had a sticker on it reading "DOT 5 fluid only"

That there is just funny :)

[Area 51%]

That there is just funny :)

Which part? Give me your email and I"ll send you a picture.

[Kai]

No, not really.

DOT 5 (actually DOT 5.0- very important!) automotive brake fluid, is silicone based- contrary to all other automotive DOT (4.1, 5.1 etc) brake fluids, which are glycol based. It is a high end product that withstands high temperatures, has no affinity to moisture (hence does not promote corrosion and freezing), has a long service life, and does not eat aviation o-rings, gaskets, seals, and other rubber components.

I have used it for years in the Sonex hydraulic disc brake setup: works as advertised!

Thx

[Scott Todd]

I thought it was funny because of earlier posters indicating how important it was to use only aviation grade brake fluid. I'm a supporter of alternate, and sometimes more modern, solutions. I agree with following most Aerospace standards but some of them are outdated. Its an Experimental airplane. I don't think there is anything wrong with substitute fluids or changing the O ring seals to be more accommodating. I have not done it and don't really care but would be curious to see what O ring material Grove uses. But as someone pointed out, I'm not qualified to understand them :)