5606/?

[DrDave]

Originally Posted by cessnadriver

Hello.
My 2 cents about MIL-H-5605. I also research this. Here is what I found. According to a hydraulic fluid expert:
MIL-H-83282 can be mixed with 5606 to improve the flame resistance BUT it can only contain not more 50%. The new hydraulic (83282) CAN NOT be used straight in older aircraft due to incompatibility of the O-rings. The reason I searched this out because I bought about 20 gallons of the new fluid to flush out my Skymaster thinking I could use straight 83282 after flushing. but found out after purchasing the new stuff I COULD NOT!
BILLS

Having read this I went back to the spec sheets on the various fluids. I found nothing describing a partial mix being acceptable and a full-strength changover unacceptable. The specific language from Shell regarding 31 and 41 and other fluids is complete compatibility. I have to question the fluid experts sources of his information. The changover instructions simply say to drain the 5606 and refill with a 83282 fluid such as 31. At this point I don't find the "expert"(s) opinion credible.