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fire proof brake fluid

glenn654

Well Known Member
I've heard of a new type of brake fluid which is much more fire resistant than the standead petro based fluid but can't find any on the market. Does anyone know where to find this stuff? Or is it a myth?

Glenn
N654RV @ OKZ
 
Its real

Hi Glenn,
It's a synthetic, fire resistant fluid named Royco 782 and I bought it at Avsco in Atlanta. The Mil-PRF-83282# should be enough. It's manufactured by Anderol, Inc. and it's packaged in quarts.

Regards,
 
Ain't no myth. Mil-H83282 has been around ever since the US Navy got tired of brake fires. Not fireproof, but about 450 flash point if I remember correctly. Crazy to use MIL-H 5606. The two are interchangable in low altitude aircraft. No seal compatibility issue, and you can mix the two fluids. No need to flush your brake system in order to make the switch; just drain, fill, and bleed. 5606 is less viscous at low temperatures, so it is still required for some hydraulic systems used in the stratosphere.
 
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Yes just don't drip it on your paint!

Dot 3 is a better paint stripper than..Paint stripper.

Now back in the UK we had Dot 5 that did not attack paint....Haven't seen it over here in the US though??

Frank
 
DanH said:
Alternate plan: Change seals and use Dot-3.
My question would be why would this be an "alternate plan" and not THE PLAN? When is the last time anyone heard of a car fire started from the brakes catching on fire? Seems to me that cars use brakes 1,000 fold more often and in harsher circumstances than any aircraft so why would we not be looking at what is used in that stopping environment as more substantial than what we currently have in aviation? Or is this another one of those things where we aviators refuse to accept that there are better systems used in other environments than what were originally designed for our aviation related systems?
 
DOT 5

Hi Frank,

DOT 5 should be readily available from most motorcycle shops. It is what Harley use in all its bikes for the very reason you mention - it doesn't damage paint. On the other hand it doesn't absorb moisture and any that gets absorbed through the rubber lines and reservoir lid can congregate at the caliper and cause corrosion.

Martin in Oz

frankh said:
Dot 3 is a better paint stripper than..Paint stripper.

Now back in the UK we had Dot 5 that did not attack paint....Haven't seen it over here in the US though??

Frank
 
Seems to me that cars use brakes 1,000 fold more often and in harsher circumstances than any aircraft so why would we not be looking at what is used in that stopping environment as more substantial than what we currently have in aviation? Or is this another one of those things where we aviators refuse to accept that there are better systems used in other environments than what were originally designed for our aviation related systems?

Not really....RV's have very small rotors, which are very thin, and which are faired to eliminate any air circulation. The rotors on a 5 inch wheel, like we have are smaller than would be used on a racing go-kart, and these rotors must stop 1600 pounds at 80 or 90 mph, and with no air circulation. (Add 200 lbs for alternate power).

This creates alot of heat, and the wheel pants prevent any flow of air to cool the rotor.

I would also point out that the high end silicone based fluids really lead to a spngy pedal, and I never let any team I raced for use that stuff. Many drivers felt the same. It is caused by Silicone fluids ability to hold bubbles.

I would hate to have a spongy pedal in a tailwheel crosswind situation. I simply used the new synthetic aircraft brake fluid.
 
Gary Bricker

There is a DOT 5.5 fluid that is high temp like 5.0 but not silicone. It has about 500 boiling temp. Dot 4 boiling point is about 375 and Dot 3 is about 325. All will absorb water which is good.
 
Gary Bricker said:
There is a DOT 5.5 fluid that is high temp like 5.0 but not silicone. It has about 500 boiling temp. Dot 4 boiling point is about 375 and Dot 3 is about 325. All will absorb water which is good.

Gary,
Might you mean DOT 5.1 instead??? This is really a "Super DOT 4" type fluid. I've never heard of DOT 5.5. Can you provide a web link that might enlighten me about it?
Charlie Kuss
 
frankh said:
Dot 3 is a better paint stripper than..Paint stripper.

Now back in the UK we had Dot 5 that did not attack paint....Haven't seen it over here in the US though??

Frank

Frank
DOT 5 has it's own drawbacks. It can cavitate during rapid brake pedal pumping. Since it does not absorb entrained moisture, that moisture drops to the bottom of the system and corrodes the caliper housing badly. (Been there, done that, got the Tee shirt!)
DOT 5 fluid was developed for the US Army. The Army is now phasing out it's use due to the above mentioned drawbacks.
The issue regarding DOT 3 & 4 fluids damaging paint is not an issue if you are using REAL paint. By that I mean a urathane or polyurathane paint like Imron, Jet Glow, Algrip, Delta or Concept, etc. These modern paints are impervious to chemical attack by most fluids including glycol based brake fluids, oils and gasolines.
Charlie Kuss
 
brake fluid

Thanks for the help guys! Am going to make the change asap to -83282.

Glenn
N654RV @ OKZ
 
On the other hand, just to fuel the fire. I've never seen a brake fire personally with 5606. I stick to servicable over a problem that is that rare. And yeah, I know you can point out a few time's it has happened with RV's, BUT I can point out a few times pilots have flown into the side of a mountain too.

I guess my point is, if not abused (REALLY hard) 5606 has zero issues in aircraft brake systems. Thicker rotors are a great idea either way. I'm planning on going with 6.00x6 tires on mine, which would reduce wheel speed at a given ground roll speed as well.
 
Wait a second, lots of info and confusion

Why not Mil spec -83282?
Are you guys really using AUTOmotive brake fluids? Really?
Is any one really using DOT 3, 4 or DOT 5 or synthetic auto transmission fluid with success in a RV?
What seal mods do I need to make and why?

I agree the higher flash and flammability of the old mil spec -5606 is not great. I had planned to use the better -83282.

From what charlie kuss, Jconard said leads me to believe that DOT anything in planes is not as desirable as the -83282.

I never considered DOT brake fluid. My concern is compatibility with seals and other "unintended consequences" of using those auto fluids. I know in the past folks who used automotive brake fluids in their RV's had major problems, seals and locked brakes. Probably the older DOT 3 or may be 4.

My plan was and still is to use mil spec -83282. I never had problems with the old seals and -5606 however I know about brake fires, thus I agree higher flash point = goodness. The only down sides of -83282, which are minor in the grand scheme of things, availability, quantity (sold in gallons) and price. The only reason -5606 is still around is because inertia, its been around for probably 40-50 years.

It would be nice if DOT X was equivalent and you could stop by the local car or motorcycle shop and buy a Pint for $3.00, but from what is sounds like -83282 is superior. I am going to stick with aircraft fluids.
 
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There are seals made for Cleveland brakes that work with the Dot 4 fluid. I know because a Dophin motor glider I worked on had that system... A nightmare to find seals, but eventually we did. Cleveland calipers with a car clutch master cylinder...
 
Is mil spec -83282 Skydrol like I think it is? If so, then for another reason against... It is the nastiest thing I ever had the misfortune to work with when I was a Delta mechanic. I can still clearly remember the caustic sting on my skin from the fluid and choking cough of the heated vapor. Did you know we always kept at least 2 bottles of caster oil in the shop. It was the preferrred remedy for anyone unlucky enough to Skydrol in their eyes.
 
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RV8RIVETER said:
Is mil spec -83282 Skydrol like I think it is? If so, then for another reason against... It is the nastiest thing I ever had the misfortune to work with when I was a Delta mechanic. (snip)


Nope. 83282 is completely compatible with 5606, and looks and acts exactly the same unless you put a match to it. AFAIK Skydrol is commonly used in heavy jets, but 83282 is more common in commuter planes and turboprops. You can google and find some accidents attributed to fires resulting from inadvertant substitution of 5606 for 83282.

I agree that brake fires are a rare problem, especially with taildraggers (because of the steerable tailwheel and less brake use). The change is so cheap and easy though, that I just don't understand why there is any resistance.

If you get stranded somewhere and need fluid, 5606 can be added to a system filled with 83282, but you will lose some fire resistence. The seals and other sytem components don't need to be changed.

I changed the o-rings in my brake calipers out for viton, because they will tolerate much higher temps. This reduces the risk of a leak if I get stupid and abuse the brakes. I didn't see any reason to change out the other seals in the system, so they remain stock (nitrile).

I vividly recall the story from the gentleman who flew his RV-8 around the world (Bill Randolph maybe?) who made a fast landing with heavy brake use while being hassled by ATC. He had a brake fire that could have been prevented by these changes, and almost lost his airplane.

We are all vulnerable to this type of pilot error, and I see this as a very cheap and easy way to buuy a little peace of mind if I ever feel the need to abuse my brakes ;-)
 
gmcjetpilot said:
Why not Mil spec -83282?
Are you guys really using AUTOmotive brake fluids? Really?
Is any one really using DOT 3, 4 or DOT 5 or synthetic auto transmission fluid with success in a RV?
What seal mods do I need to make and why?


I agree the higher flash and flammability of the old mil spec -5606 is not great. I had planned to use the better -83282.


From what charlie kuss, Jconard said leads me to believe that DOT anything in planes is not as desirable as the -83282.


I never considered DOT brake fluid. My concern is compatibility with seals and other "unintended consequences" of using those auto fluids. I know in the past folks who used automotive brake fluids in their RV's had major problems, seals and locked brakes. Probably the older DOT 3 or may be 4.

My plan was and still is to use mil spec -83282. I never had problems with the old seals and -5606 however I know about brake fires, thus I agree higher flash point = goodness. The only down sides of -83282, which are minor in the grand scheme of things, availability, quantity (sold in gallons) and price. The only reason -5606 is still around is because inertia, its been around for probably 40-50 years.

It would be nice if DOT X was equivalent and you could stop by the local car or motorcycle shop and buy a Pint for $3.00, but from what is sounds like -83282 is superior. I am going to stick with aircraft fluids.

Hi George,
Yes we are using DOT 4 or DOT "super 4" (aka DOT 5.1) fluids. You need to swap out all the Nitrile O-rings in the system for identical items made of EDPM (ethylene propylene). You also have to swap out any rubber based brake hoses (Such as Aeroquip 303) for Teflon lined hoses (like the ones used on auto race cars) The Teflon hoses have the added advantages of being lighter, less expensive and having higher pressure ratings. The down side to them is that they are not as flexible as the rubber hoses.


If you don't want to swap out the seals, go with 83282 or synthetic ATF (they are essentially the same fluid). Also swap out the caliper O-ring for one made of 70 Durometer Viton. Nitrile has a service temp ceiling of 250 degrees Fahrenheit, while the Viton is rated to 450 degrees.
The typical failure mode of the Nitrile (aka Buna N) O-rings is that they get stiff and shrink from excess heat. Once this happens, the fluid slowly oozes out, until the day you need to really stomp on the binders to stop. Then those leaky O-rings spray the fluid onto your red hot (1100 degrees +) brake rotors. This is why I believe that "improved fluid" is just an exercise in semantics. When flammable fluid hits a rotor whose temp is over 450 degrees, it won't matter if it 5056 or 83282. Both of them WILL ignite.


I'll agree to disagree regarding the superiority of ANY mineral based oil brake fluid compared to a quality DOT 4 or DOT 5.1 fluid.


To each his own. If you stick with the approved fluids, at least upgrade your caliper O-rings to the above mentioned Viton units. I do have one question to ask you George.
If mineral oil fluids are so great, why does every other type of motorized vehicle (including airliners) use glycol based fluids???? FYI, Skydrol is a glycol based fluid. It's the glycol based fluid from ****! :)
I've spoken at length with the engineers at Cleveland and they have admitted that the reason they still specify 5056, is because the cost to re-certify with a better fluid is money. The market size doesn't warrant the effort and expense for them.

Just my opinions
Charlie Kuss
PS PS Don pointed out to me [on the next page] that I am in error in my statement above. Skydrol is phosphate ester based, NOT glycol ester.
 
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RV8RIVETER said:
Is mil spec -83282 Skydrol like I think it is? If so, then for another reason against... It is the nastiest thing I ever had the misfortune to work with when I was a Delta mechanic. I can still clearly remember the caustic sting on my skin from the fluid and choking cough of the heated vapor. Did you know we always kept at least 2 bottles of caster oil in the shop. It was the preferred remedy for anyone unlucky enough to Skydrol in their eyes.

No,
5056 and 83282 are both mineral oil based fluids, similar to automatic transmission fluid. They burn like any other mineral oil.

Skydrol is the "aviation big iron" adaptation of automotive brake fluids. It is glycol based, like DOT 3 or 4 based fluids, but the similarities end there. Skydrol is indeed nasty stuff. It burns the skin and can do great damage to your eyes. It is also a carcinogen (causes cancer).
For our uses, automotive fluids or the approved general aviation fluids are better choices.
Charlie Kuss
PS Don pointed out to me that I am in error in my statement above. Skydrol is phosphate ester based, NOT glycol ester.
 
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chaskuss said:
No,
5056 and 83282 are both mineral oil based fluids, similar to automatic transmission fluid. They burn like any other mineral oil.

Skydrol is the "aviation big iron" adaptation of automotive brake fluids. It is glycol based, like DOT 3 or 4 based fluids, but the similarities end there. Skydrol is indeed nasty stuff. It burns the skin and can do great damage to your eyes. It is also a carcinagin (causes cancer).
For our uses, automotive fluids or the approved general aviation fluids are better choices.
Charlie Kuss


Thanks again Charlie for the O-ring set and info. I may actually get to finally use them in the next 6 months. :)
 
My experience with DOT 5 silicone brake fluid

Due to several brake fires in EZ's that ended up destroying the airplanes, Burt Rutan published in his RAF newsletter, Canard Pusher 54-Pg4, July 1987: "We highly recommend the 100% silicone brake fluid (must be Dot 5). Since it is completely inert, compatible with any type "O" rings and seals. It is not flammable and it does not destroy your paint as normal aircraft brake fluid does. We bought it at a Hot Rod-type auto parts store locally."

I personally changed the brake fluid in my Long-EZ from "ruby red" to DOT 5 purple fluid and never had any trouble in 20 yrs of running the fluid in my EZ.
 
Skydrol facts

Skydrol is the brand name of one type of phosphate ester (not glycol) synthetic hydraulic fluid made by Monsanto. It is indeed nasty stuff that melts paint, softens nitrile seals, stings skin and eyes, and tastes bad, but according to the MSDS will not cause cancer or other physical harm if used as directed. If that was the case, I'd be blind and/or dead years ago. I still wear the same hard contacts splashed with the stuff for 20 years with no damage to them or me.

It is used in virtually all modern civil transport aircraft as an answer to meet Part 25 certification requirements for rejected takeoff brake fires. To get an idea of the tests required see - http://www.liveleak.com/view?i=921_1179536523&c=1

If you think DOT anything can pass muster under those conditions, guess again. If so they wouldn't have had to invent something new like Skydrol. About the only place red fluid is used in transports is in strut shock struts. Cars and aircraft operate in two completely different environments. I'd vote on sticking with proven aircraft fluids. Would I use Skydrol in an RV to make sure I wouldn't get a brake fire? Nope -its overkill. Would I use MIL-5656 when 83282 is available? Again nope.

Don
 
Minor note; Pilots in the arctic regions should be aware of a possible sealing issue with Viton o-rings when things are very cold. Nitrile will seal at slightly lower temperatures than Viton. Check specs.
 
A few years ago and not knowing better, I used DOT 3 on my RANS S-12XL. The seals in the master cylinder and the wheel cylinders started leaking about 3 weeks later and shortly thereafter----no brakes.
 
Amber auto brake fluid DOT 3?

I don't know which DOT number standard auto brake fluid is (the amber colored stuff that also substitues for paint remover), but it is a definate DO NOT USE because it will soften and wreck the o-rings in aircraft brake pucks & master cylinders!!
 
I used Mobile 1 Synthetic ATF. I read another thread here on VAF that someone had been using it for several years with good results. I've only had it in my brake lines for about 2 weeks...so far, so good.
 
There is a DOT 5.5 fluid that is high temp like 5.0 but not silicone. It has about 500 boiling temp. Dot 4 boiling point is about 375 and Dot 3 is about 325. All will absorb water which is good.

Gary
Can you point me to some "online" info about DOT 5.5? I am familiar with DOT 5.1, which is a glycol ester based (like DOT 3 & 4) fluid. However, The great sounding specs for 5.1 are a bit of a mirage. For "real world" usage of glycol ester (automotive) brake fluids, you need to judge the fluid on it's "wet" rather than "dry" performance ratings. DOT 5.1 has fantastic "dry" performance, but that performance falls off of the proverbial cliff once "wet".
These DOT 5.1 fluids are expensive and not available except at "race car" shops. That is their main target group, racers. For a race car team, changing the brake fluid between every race is not a big deal. For the average RV owner, once a year or every other year is a more realistic fluid flush time frame.
While DOT fluids WILL ruin old lacquer or early enamel paints, they won't harm any of the newer urathane or polyurathane paints commonly used to paint aircraft. That arguement is simply a rationalization to not use them. Those who have suggested the newer synthetic MIL-Spec products in conjunction with Viton caliper O-rings or DOT 5 silicone fluids are better off than simply using the old style Buna N (250 degree F working temp) O-rings.
Charlie Kuss
 
Skydrol is the brand name of one type of phosphate ester (not glycol) synthetic hydraulic fluid made by Monsanto. It is indeed nasty stuff that melts paint, softens Nitrile seals, stings skin and eyes, and tastes bad, but according to the MSDS will not cause cancer or other physical harm if used as directed. If that was the case, I'd be blind and/or dead years ago. I still wear the same hard contacts splashed with the stuff for 20 years with no damage to them or me.
snipped
Don

Don
I stand corrected regarding Skydrol being a carcinogen. I was told it was by one of the Cleveland engineers I spoke to. It appears that only 'some" of them are. I just did a Google search for Skydrol MSDS, see

https://team.solutia.com/sites/msds/Lists/MSDS%20Search%20Tool/WebView.aspx?FilterField1=Business&FilterValue1=Skydrol&View={0CCE272C-0BFB-4CD6-8EC7-F3FA7EA386C7}

It appears that Skydrol PE-5, & LD4 DO have "limited evidence of a carcinogenic effect". However, Skydrol 5 and Skydrol 500B4 do not. However, there is mention of adverse effects to the bladder.

I have no first hand experience with Skydrol, as Don has. I must ASSume that Skydrol 5 is what is commonly used on most aircraft brake systems. Thanks for the additional info.
Charlie Kuss
 
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No problem Charlie. The B4 stuff is what has been in service for years. Another interesting thing about it is it is a better lubricant than mineral based oils, so it helps component life. Like I said though, it's nasty stuff to work with and makes a good stripper for urethane, or any other, paint.

I've lived in the bigger aircraft world my whole career, but really enjoy learning about the smaller stuff here. Lots of great experiences and ideas in the experimental community. I think most of the advances in small certified aircraft are because the experimental builders are giving the manufacturer's a high bar to hit. :)

Don
 
I have a 1991 Harley Sportser that's had DOT5 silicone fluid in it since new (17 years now). The bike's brake reservoirs are sealed against the atmosphere, though, and that probably helps tremendously to keep water out. As long as you don't ever allow any moisture to enter the sealed system, DOT5 will last practically forever and the insides of the master cylinders and disc caliper cylinders will stay pristine inside, but allow any water in, and the aluminum at the bottommost point of the calipers' cylinders and pistons is doomed. I've never had any problems with spongy brake feel either. Ensuring the brake fluid reservoir system on an aircraft stays sealed against the atmosphere while still being able to expand and contract a trapped dry air volume above the fluid level in the reservoir might be a bit of a technical challenge, but certainly not impossible. Shaking the fluid up and getting bubbles suspended in the liquid from doing a lot of acro, or landing/taking off on rough turf strips might contribute to a spongy pedal feel, but then my motorcyle never had to deal with acro (except once, don't ask :eek: )
 
stat-o-seals

If anyone else is using or planning to use EPDM seals in their brake system for DOT-3,4, or 5.1 fluid, be aware that the master cylinders contain not just the three o-rings, but also a stat-o-seal. It's basically a washer with rubber molded around the inside diameter. The stat-o-seal as supplied from Matco is Buna-N (Nitrile). The part number of an EPDM stat-o-seal is NAS1523-3P. I had a heck of a time finding these, but finally found some.

20101122-10-tn.jpg


20101122-11-tn.jpg


I had to meet a minimum order, so I have a few left. If anyone wants some, they're $4.50 each while my supply lasts.

Take care,
 
I just did my breaks yesterday. I used Mobile 1 synthetic ATF that I purchased at AutoZone. About 15 minutes and it was done. Now I can start the engine.

Pat
 
Mobile 1 synthetic ATF data point

I installed Mobile 1 synthetic ATF two years ago when I was about ready to fly.

So far so good!

Mark
 
I have been flying with Mobil 1 ATF for a little over 5 years and 340 hours with stock parts. No signs of leaks or seal problems. The flash point of Mobil 1 ATF is quite high, which is what attracted me to use it in the first place (along with endorsements from other builders who had gone before with good results)
 
BUMPing the thread!

How you guys and Mobil 1 ATF on stock Vans Parts holding up?

Getting the mil 8xxxx stuf in South Africa is almost impossible, dont want to import, cause it will cost a arm and a lef.

Need to know for my RV10:confused:

Rudi
 
Rudi,

Been using Mobil 1 Synthetic ATF for almost a year and 90 hrs so far with stock Van's brakes, master cylinders etc. Not so much as a drop of a leak and the brakes work normally. No issues at all.
 
To the Mobil 1 ATF guys...it seems like excellent news! :D

Last Question: How corrosive is mobile 1 ATF in case you do get a leak or brake line failure to your paint and structure?
 
With a free castoring nose wheel, a long taxi in a heavy cross wind can cause heating from the prolonged braking on one side. Viton O rings have a much higher temperature rating than Buna N. The Viton seals are harder and less flexible but by the book they are more compatible with the Mobile 1 synthetic ATF.

I have been using the Mobile 1 synthetic ATF fluid in my Rocket for about 50 hours now with no leaks or issues. I have Viton O rings in the wheel cylinders on the right side, and the original Buna N O rings on the left side. Both sides are fine. When I change the tire on the left side, I will install the Viton O rings there as well. Some people have concerns about Viton in colder temps. I have been flying at -15 and -20 a few times with no problems or leaks.
 
Stock brakes, mobil 1 ATF for 2 years, 230 hrs

I have 230 hours on mine and everything is perfect so far. No leaks, no problems. Just finished my second annual. The ATF looks just like it did the day I put it in. This is on an A model too, so I may use brakes a bit more than the tailwheel guys.

ATF is designed to work just fine at high temperatures without attacking the aluminum transmission that it is (normally) contained in. It's viscosity is pretty stable with temperature and its flashpoint is fairly high. It's also available in any small town you might happen to be in. That's a big selling point for me. I didn't want to be like the round-the-world guy stuck in SE Asia trying to figure out what to use for brake fluid.
 
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While we are talking about brake fluid, is anyone aware of a fluid that is compatible with viton seals? The Mobile 1 ATF? Temperature issues won't come into play as this is for a hydraulic clutch.
 
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