Aircraft Brake Fluid

[170C]

I have a couple of containers of "Aircraft Hydralic Oil 15" and one or more that I believe say "Aircraft Hydralic Oil 5606G". Are these two products compatable? Can or should they be combined?

[Harold Holiman]

Frank,

I would think they are compatible, but, George probably knows. I used to get different looking containers from different sources but never actually looked at the numbers, assuming that they all met military or aircraft specs.

Harold

[DaveF]

This web site http://www.tpub.com/content/chhelicopte ... 10_118.htm says the following substances are compatible

APPROVED DOMESTIC COMMERCIAL FLUIDS FOR MIL-H-5606 Manufacturer’s Designation: PQ 2890/2863/2903/2905/2950/4140/3808/4328 Mobil Aero HFD Stauffer Aero Hydroil 500 Brayco 757B/756F/756ES/756E Brayco Micronic 756ES TEXACO Aircraft Hydraulic Oil 15/TL-10711 Cheveron Aviation Hydraulic Fluid D PED 5225 Penreco Petrofluid 4606/4146/4607 Royco 756C/756D/756E Castrol Hyspin A Aeroshell Fluid 41

[170C]

Thanks for the data showing that MIL-H-5606 converts to Texaco 15. Both of mine are Texaco, one with 15 and as mentioned earlier, one is 5606. I now feel they can be combined without any problem. Funny thing is that over the past 26+ years I doubt that I have used more than a quart of the stuff and between a purchase and gifts, I have nearly 3 gallons.

[blueldr]

Back in the olden days they used to have a green, (or was it blue) hydraulic fluid for use in some of the the brake systems that had
natural rubber seals where petroleum based fluid would raise hell. It was real gummy stuff where it leaked out and dried, and was
soluable in alcohol rather than a petroleum solvent. I think it was some kind of a vegatable oil base. I remember that it was used in
the brakes of the Beech AT-7 and AT-11 trainers, maybe others too.
I do remember that mixing the two absolutely raised hell in a system. A guy had to be pretty stupid to do that considering that they
went to the trouble of dyeing them two different colors. However, in view of "Murphys Law"----------.

[GAHorn]

Back in the olden days they used to have a green, (or was it blue) hydraulic fluid for use in some of the the brake systems that had
natural rubber seals where petroleum based fluid would raise hell. It was real gummy stuff where it leaked out and dried, and was
soluable in alcohol rather than a petroleum solvent. I think it was some kind of a vegatable oil base. I remember that it was used in
the brakes of the Beech AT-7 and AT-11 trainers, maybe others too.
I do remember that mixing the two absolutely raised hell in a system. A guy had to be pretty stupid to do that considering that they
went to the trouble of dyeing them two different colors. However, in view of "Murphys Law"----------.

bluEldr, I believe you are referring to what is commonly referred to as "Girling" brake fluid, and it was indeed dyed for identification. It is almost never seen these days.
Another type of synthetic hydraulic fluid used in airplanes is "SkyDrol", which is dyed purple. It will eat aluminum and is very caustic, used mostly in high-altitude, high-pressure systems because it flows readily in sub-temperatures and is non-flammable. It should never be mixed with petroleum fluids such as Hyd-5606.
Frank, the Texaco H-15 is only their "brand name" for the product, and is actually 5606 and is probably identified on the can as such.

[blueldr]

George,
I think Skydrol was used in the pressurization system in the DC-6. I didn't remember that it was detrimental to aluminum.
All the rest of the hydraulics on the DC-6 used 5606.

[c170b53]

Mil 5606 still used in Oleos for most aircraft, so hang on to it like most of us do Frank.The symbol blue-yellow-blue was adopted to indicate a hydraulic system and as such barrels of 5605 where painted the same. That is until the jet age came where Skydrol was introduced with a few expensive mix ups occurring as the hydraulic lines where still labeled the same but the fluids are not compatible. Skydrol comes in a few varieties, small differences in Mil spec. It doesn't eat aluminum but eats most protective coatings around the aluminum which of course I guess leads to corrosion occurring (that's probably what you meant George ). Those of us used to the stuff know why you must wash your hands thoroughly after contact, otherwise a reminder later.

[hungstart]

Another type of synthetic hydraulic fluid used in airplanes is "SkyDrol", which is dyed purple. It will eat aluminum and is very caustic

I don't know where you got your information George, but Skydrol is not caustic nor will it hurt aluminum, if it were we would not be able to use any aluminum in the hydraulic systems. If you look you will see a tremendous amount of aluminum fittings and lines used in the return, reservoir, and vent systems in transport category aircraft. Now it will strip paint very well and it will dissovle some of the early resins and adhesives used in composite materials. We once changed a carbon graphite elevator on a MD-11 because of dis-bonding of the ribs and skin from a prolonged Skydrol leak at a gust damper.
I remember and blueldr probably does to, when the Monsanto rep came around part of his demonstration was to drink some Skydrol.

[Showboatsix]

Quote: "Skydrol fluids are approved by all airframe manufacturers specifying phosphate ester hydraulic fluids, including the following material specifications:

Airbus Industrie NSA 307.110
Boeing Long Beach DMS 2014
Boeing Seattle BMS 3-11
British Aerospace BAC M.333.B
Lockheed Aircraft Corp. LAC C34-1224
Society of Automotive Engineers AS 1241
Fokker "

I guess that "the self anointed one is wrong"


http://www.skydrol.com/pages/materials_chart.asp
http://www.skydrol.com/pages/product.asp

[c170b53]

Well fortunately the 170 doesn't need the stuff and Frank if the Texaco cans are really old they maybe worth something to a collector or as an auction item . I know this is bad karma but you got to like the reliability of the brake cylinders in a 170.

[170C]

Thanks Jim. I don't know how old these containers are, but doubt they are of such vintage to be valuable. One round gallon can is full, never opened and the other one is also round, but has been opened and the two small holes have been taped closed every since I have had possession of it. Hoping the fluid is still good. The other one is also metal, but is squared off (retangle) with a screw-on lid. You are correct, we don't have much of a problem with our brake system.

[170C]

GEEZE! Can't a guy be wrong sometime without someone just waiting in the shadows to jump at the opportunity to point out the error George may have missed this one, I don't personally know, but consider the number of correct data vs the few where he is mistaken and give the guy a break. I don't notice the naysayers stepping up to volunteer to help sort out a lot of the data being requested on a daily basis. When someone does comment on something on the forum and it turns out to be in error, its good to point this out, but there is no need to be surley about it.

[GAHorn]

Well, as Jim pointed out, I merely had an unfortunate choice of words when I said it will "eat aluminum". As Jim notes, it will destroy many protective finishes ...which are used to protect aluminum... and therefore is a common contributor to corrosion issues. Anyone who has ever worked on any of the aircraft using it, (Grumman/Gulfstreams comes immediately to mind) will remember the corrosion issues we always had with Skydrol which we never had with 5606. When I said "caustic"... just spill some and see how long you fail to notice it.

Frank, that Texaco 15 is suitable for use in all our brake systems and in most other GA aircraft where 5606 is called out.

That unopened can is a good candidate for a Xmas gift or auction item. (If the opened cans have not been contaminated then the fluid should be just fine. Texaco 15/5606 does not deteriorate rapidly if it's not openly exposed for long periods. I've had two of the rectangular cans opened for at least a decade and they are just fine. I use them for replenishment purposes.

[Kellym]

If you want to enhance the safety of your brake system, drain the 5606 from the system, as a fire prone anachronism, and get yourself some much more fire resistant fluid. You can purchase by the quart and/or a gallon at Skygeek.



http://www.skygeek.com/royco-782-synthe ... fluid.html

Aeroshell 31 is another brand, but harder to find by the quart.