Looking for fire resistant hydraulic fluid alternative.

[lombardo]

Hi,
I´m looking for a fire resistant hydraulic fluid such as the Skydrol LD4, do you know another alternative that meets the MIL 0646 requirements, I need to have more alternatives not only the solutia Skydrol?
Thanks in advance
Alejandro Peterson

 

[diamondjim]

Is there a QPL listed for this?

 

[kontiki99]

The military never used skydrol as far as I know. They used to use a vegetable based fluid, that I know has since been replaced with a synthetic version. Off the top of my head I don't know the spec.

It's the same fluid used inside an oleo strut of a commercial aircraft.

 

[swall]

Mil-H-5606 oil?

 

[thruthefence]

MIL-H-83282

supposedly a direct replacement for 5606, but more fire resistant.

Used in the Cessna Citation "CJ" series. Much friendler to us maintenance folks then skydrol

 

[kontiki99]

Thanks Swall and Thruthefence. Those were the specs I couldn’t recall.

When I was in the USMC (as a wee lad), hydraulic fluid was 5606 (A6Es around 1974).

Most of my heavy jet wrench time I was around and way too often in Skydrol. That's some nasty stuff!

Years later while working my way through school I did a stint with a commuter outfit and saw MIL-H-83282.

Much nicer to work around.

 

[kdwhite]

You might also consider MIL-PRF-87257 (NATO H-538). This fluid is a little harder to find but has slightly better viscosity at low temperatures compared to MIL-H-83282 (NATO H-537). 87257 is "rated" for -54C to +200C while 83282 is for use in the range of -40C to +205C. As I recall, neither are quite as good as good ole MIL-H-5606 at lower temperatures. But MIL-H-5606 burns readily. These others burn slowly and in most conditions will self extinguish.
I would not use Skydrol unless I had compelling reasons to do so.