The International Cessna^® 170 Association

To keep brake master cyl plugs (and spilled 5605 fluid) from going into the belly, I always pack rags around the master cyls completely closing up the opening. It only takes a second and eliminates the biggest anxiety item in the whole job, dropping something into the abyss. It's especially easy when I can get Ina to do it for me.

There should never be any chance of air being introduced into the system when filling from the caliper bleed plug (no matter what kind of pump/squeeze device is used) IF a length of clear vinyl tube is used between the pump and the bleed fitting.

The clear vinyl tube can be purged before it is attached to the bleeder until no air is seen inside it and then once attached to the bleeder enough fluid can be circulated thru the system (it doesn't take much) to the master cyl reservoir to pass thru any air trapped in the bleeder. That is why a 1/8" discharge clear vinyl tube attached to the master cyl reservoir with a 1/8"NPT x 1/8" plastic hose barb and going into a jar is the key to the process. Fluid can be circulated until no air is left.

I have found it is not a good idea to store 5606 in a plastic container, some of them will soften up over time and the fluid seems to get contaminated. I use the steel oil pump can and wash it out thoroughly with 100LL avgas after every job is over. 5606 will tend to clot up if stored in the pump can and it's hard on the pump seals.

I wonder if I'm the last guy that still remembers brake systems thst used "Blue" fluid instead of "Red'? The early Twin Beech
( 18 series ) airplanes such the AT-7, AT-11, and C-45, used "Blue" brake fluid which was, If memory serves, a vegtable base
fluid that had to be cleaned up with alcohol. Spills seemed to evaporate to a terribly gummy residue. I believe that perhaps the brakes in those days had natural rubber internal parts that would be rendered "hors de combat" in a petroleum base fluid. Synthetic rubber products for parts that were impervious to petroleum came along during WWII.

BL-
Sure you're not talking about lav fluid?

Richard,
Thee "Blue" hydraulic fluid was not quite as dark blue as the fluid we poured in the biffy.

From plagiarized personal notes:
Three types of hydraulic oil are commonly used in aircraft: vegetable, mineral and synthetic based. Each having their own properties and requirements.

Vegetable
Colored blue and made from castor oil and alcohol. Mostly used on older aircraft where natural rubber seals are used (until they are replaced with synthetic types). Can cause sludge and corrosion.

Mineral
Colored red and based on a widely used kerosene petrochemical product. Good lubricating properties with additives inhibiting corrosion and foaming. Very stable and low viscosity change with temperature changes. May not be used with natural rubber and is flammable.

Synthetic
Colored purple and less flammable than the mineral type. Base on synthetic (man made) phosphate ester and tends to attract water (moisture) and attacks certain plastics and paint. Can degrade aircraft wiring eating away the insulation. Known as Skydrol and other grades are dyed green or amber.

George, You Da Man!

gahorn wrote:From plagiarized personal notes:
Three types of hydraulic oil are commonly used in aircraft: vegetable, mineral and synthetic based. Each having their own properties and requirements.

Vegetable
Colored blue and made from castor oil and alcohol. Mostly used on older aircraft where natural rubber seals are used (until they are replaced with synthetic types). Can cause sludge and corrosion.

Mineral
Colored red and based on a widely used kerosene petrochemical product. Good lubricating properties with additives inhibiting corrosion and foaming. Very stable and low viscosity change with temperature changes. May not be used with natural rubber and is flammable.

Synthetic
Colored purple and less flammable than the mineral type. Base on synthetic (man made) phosphate ester and tends to attract water (moisture) and attacks certain plastics and paint. Can degrade aircraft wiring eating away the insulation. Known as Skydrol and other grades are dyed green or amber.

I'll add one other characteristic to the Skydrol; DONT get it in your eyes, burns like paint stripper, much harder to wash out

Off topic, but why would I receive a "topic reply notification" 5 years late? This is not uncommon for me to receive these notifications from this website; no new content in the thread. It is not bothersome at all, in fact I enjoy re-reading the old post. It does remind me how fast life slips by.

In this particular case, I mistakenly posted to this thread which created the notice you received. I then realized I had the wrong thread and deleted my post. The software does not and can not rescind the notice sent you. BTW you receive these notices because you indicated at the bottom of the thread that you want a notice sent you. To stop receiving these notices un check this box.

You can also go to the User Control Panel in the upper left of each window, choose Manage subscriptions, and it will list all threads you are subscribed to
On the right of each thread on the list you can choose to unsubscribe.

Bruce,
I thank you kindly for the instruction. I did say that this is not bothersome at all, and I mean this. No worries, I was only curious why it happens. I still am unable to cabbage on to the transmission of how it all works. I don't care. I like reading old post.
I know how to check the appropriate box. No need to. Again, I like to receive 5 year old topic reply notifications. No worries.