Brake Fluid / Rubber Compound Compatibility


britmcman99
 

Hello Sam:

I have not repaired Airhearts, but they must make a rebuild kit, and if the
cylinders have pitted surfaces, they need to be honed just like any other
brake cylinder. I have done lots of Triumph car slave and master cylinders in
this way. Gasket seals, compression seals, cylindrical cup seals - what else
is there to do? How about use the appropriate rubber kit for the appropriate
brake compound? According to published Airheart literature:


"...Make certain that the master cylinder you are using has the correct
seals to be compatible with the hydraulic fluid being used in the braking system.
Master cylinders with EPR seals are designed for use with automotive brake
fluid which meets the standards of SAE-J-1703 and DOT-3. Master cylinders
with Buna-N seals are designed for use with mineral base "Red" hydraulic fluid
which meets the standards of Mil-Spec. MIL-5606..."

There is better than a good chance the cylinders are fine but which have at
some time been cross-contaminated with the incorrect brake fluid.


_http://www.airheart-brakes.com/partsheets_airheart.html_
(http://www.airheart-brakes.com/partsheets_airheart.html)

Cheers,

Phil





************************************** See what's free at http://www.aol.com.


britmcman99
 

Hello Sam:

Good to know you are an A&P. I don't have any secrets as to how to keep an
Airheart master cylinder from leaking other than by following good assembly
practice. I am still surprised at how really very qualified people often make
very obvious lapses in good judgement or overlook a simple thing like fluid
compatability.

If all else fails, don't put fluid in it.

Am I to understand that you might be coming to Jean? I'd love to learn some
Spanish.

Cheers,

Phil



************************************** See what's free at http://www.aol.com.


Sam Hoskins
 

Phil, I'm an A&P. We do know things like fluid compatibility and pitted
surfaces.

Over the years I have both rebuilt and replaced the Airheart master
cylinders. One leaks, the other doesn't. I may pop for a brand gnu set,
just to see what happens.

Regards,

Sam

On 4/25/07, britmcman@... <britmcman@...> wrote:

Hello Sam:

I have not repaired Airhearts, but they must make a rebuild kit, and if
the
cylinders have pitted surfaces, they need to be honed just like any other
brake cylinder. I have done lots of Triumph car slave and master cylinders
in
this way. Gasket seals, compression seals, cylindrical cup seals - what
else
is there to do? How about use the appropriate rubber kit for the
appropriate
brake compound? According to published Airheart literature:


"...Make certain that the master cylinder you are using has the correct
seals to be compatible with the hydraulic fluid being used in the braking
system.
Master cylinders with EPR seals are designed for use with automotive brake

fluid which meets the standards of SAE-J-1703 and DOT-3. Master cylinders
with Buna-N seals are designed for use with mineral base "Red" hydraulic
fluid
which meets the standards of Mil-Spec. MIL-5606..."

There is better than a good chance the cylinders are fine but which have
at
some time been cross-contaminated with the incorrect brake fluid.

_http://www.airheart-brakes.com/partsheets_airheart.html_
(http://www.airheart-brakes.com/partsheets_airheart.html)

Cheers,

Phil



************************************** See what's free at
http://www.aol.com.




--
Sam Hoskins
www.MistakeProofing.Net
618-967-0016 ph.
312-212-4086 fax


raoborg@...
 

Hi Sam. I have a new one that I am not going to use. I have put in toe brakes with Cleveland cylinders and a reservoir.I do not accept Mexican pesos though. Let me know Raoul

--- sam.hoskins@... wrote:

From: "Sam Hoskins" <sam.hoskins@...>
To: Q-LIST@...
Subject: Re: [Q-LIST] Brake Fluid / Rubber Compound Compatibility
Date: Wed, 25 Apr 2007 21:36:45 -0500

Phil, I'm an A&P. We do know things like fluid compatibility and pitted
surfaces.

Over the years I have both rebuilt and replaced the Airheart master
cylinders. One leaks, the other doesn't. I may pop for a brand gnu set,
just to see what happens.

Regards,

Sam

On 4/25/07, britmcman@... <britmcman@...> wrote:

Hello Sam:

I have not repaired Airhearts, but they must make a rebuild kit, and if
the
cylinders have pitted surfaces, they need to be honed just like any other
brake cylinder. I have done lots of Triumph car slave and master cylinders
in
this way. Gasket seals, compression seals, cylindrical cup seals - what
else
is there to do? How about use the appropriate rubber kit for the
appropriate
brake compound? According to published Airheart literature:


"...Make certain that the master cylinder you are using has the correct
seals to be compatible with the hydraulic fluid being used in the braking
system.
Master cylinders with EPR seals are designed for use with automotive brake

fluid which meets the standards of SAE-J-1703 and DOT-3. Master cylinders
with Buna-N seals are designed for use with mineral base "Red" hydraulic
fluid
which meets the standards of Mil-Spec. MIL-5606..."

There is better than a good chance the cylinders are fine but which have
at
some time been cross-contaminated with the incorrect brake fluid.

_http://www.airheart-brakes.com/partsheets_airheart.html_
(http://www.airheart-brakes.com/partsheets_airheart.html)

Cheers,

Phil



************************************** See what's free at
http://www.aol.com.




--
Sam Hoskins
www.MistakeProofing.Net
618-967-0016 ph.
312-212-4086 fax








_____________________________________________________________
Netscape. Just the Net You Need.


Bob Moehlenkamp <bobmoeh@...>
 

I saved this article a while back. Thought it was interesting. I would
think Nylo tubing would melt and add to the fire.
Bob MO

This was posted on the Biplane Hangar Mailing list recently:
Bret - Biplane Hangar http://www.gf24.de/biplane/
<<Gang,
Had a brake fire on an RV-8A last weekend. Tidy combination of
operator error and design issues, much of which is specific to the 8A
and/or castering nosewheel, steer-with-the-brakes airplanes in
general. However, research did turn up a few items perhaps everyone
should know.

The fire started after an overheated caliper leaked fluid on a
hot disk. The fluid flashed and lit the resin in the fiberglass wheel
pant, as well as the tire sidewall. The brake worked fine, with only
slightly higher pedal pressure required even when on fire.
I've posted a photo to the vault (yep, a bystander had a digital
camera). In the photo, I'm holding pedal pressure while shutting down
for the fire crew. Note the fire on the ground under the pant,
believed to be fluid and dripping resin. I don't recall any
additional pedal travel.

When something like this happens I get curious. Why did the seal
leak at some temperature well below a failure temperature for the rest
of the brake? And why did the fluid catch fire?

Fast forward: It turns out the Cleveland piston seal for the
little 30-9 caliper is an ordinary MS28775-218 nitrile o-ring.
Nitrile's temperature rating is - 65F to +275 F. We found the seal to
be brittle and flaking when we dismantled the caliper. A caliper seal
with a 275 F temp limit is below automotive standards, but that's
another story.

As for fluid, Cleveland's tech manual specifies either Mil-H-5606
or Mil-H-83282 as acceptable. Both are listed in AC-43 and the A&P
texts. Turns out that Mil-H-83282 was created because the military
was tired of setting it's airplanes on fire. Mil-H-5606 is the
standard red hydraulic fluid sold by Spruce, Wicks, Chief, etc. It is
a petroleum base, and turns out to have a very low flash point. The
Mil-H-83282 is also red, and compatible with 5606 fluid as well as
seals created for 5606. However, it is a synthetic, with much higher
flash and burn points, and is self-extinguishing when removed from the
ignition source.

You can download complete specs for Aeroshell Fluid 41
(Mil-H-5606) and Aeroshell Fluid 31 (Mil-H-83282) at:

http://193.113.209.166/aeroshell/aeroshellhydraulicfluids.pdf

Note the flash points of the two fluids. Aeroshell 41 is 104 C,
which is only 219 F. Aeroshell 31 is 237 C, or 458 F.

A flash point of 219 F means that when a Cleveland caliper seal
fails at something above 275, the fluid is already hot enough to light
when it hits a hot disk and vaporizes inside the pant. Makes for an
interesting combination.

Live and learn. I always assumed standard "mil-spec red brake
fluid" was something special, and I doubt I was alone in this
assumption. It's not. It's just another one of those "always done it
that way" things prevalent with light airplanes. Note that the Shell
literature declines to even refer to it as brake fluid.

Spruce, etc, doesn't sell Mil-H-83282 fluid, but they should.
I've already ordeting combination.

Live and learn. I always assumed standard "mil-spec red brake
fluid" was something special, and I doubt I was alone in this
assumption. It's not. It's just another one of those "always done it
that way" things prevalent with light airplanes. Note that the Shell
literature declines to even refer to it as brake fluid.

Spruce, etc, doesn't sell Mil-H-83282 fluid, but they should.
I've already ordered a gallon of Fluid 31 from the local Shell
distributor. Since the old and new fluids are compatible, switching
is as easy as draining the old, flush with new, refill, and bleed.

Let's be careful out there.

<Dan

on 1/29/04 4:59 PM, PullSomeGs@... at PullSomeGs@... wrote:

A coworker has asked me to gather any information on wheel pant
fires for his friend who's Extra burned. Apparently he had a fuel
drain that exited on the wheel pant, which somehow caught fire. He is
having trouble with his insurance company and wants to have some other
cases of such an event to help his case. Seems like I remember this
happening to someone a few years ago. Any information is appreciated!


Jim Patillo
 

Phil,

Please get ahold of me asap. 510-468-4891.

Thanks
Jim P.

--- In Q-LIST@..., britmcman@... wrote:

Hello Sam:

Good to know you are an A&P. I don't have any secrets as to how
to keep an
Airheart master cylinder from leaking other than by following good
assembly
practice. I am still surprised at how really very qualified
people often make
very obvious lapses in good judgement or overlook a simple thing
like fluid
compatability.

If all else fails, don't put fluid in it.

Am I to understand that you might be coming to Jean? I'd love to
learn some
Spanish.

Cheers,

Phil



************************************** See what's free at
http://www.aol.com.