Originally Posted by
Lonewolf_50
That fluid has been replaced by 83282, about 30 years ago. Only you can prevent in flight fires.
We were still using MIL-H-5606E or F (more fire resistant than 5606A,B,C, or D I presume) in 1989 in US Army UH-60As, so the switch in Army birds might have come along a little bit later. GW1 maybe?
In any event, It never appeared to me that Chinook and Huey crews were as concerned about hydraulic seeps as we were in the Blackhawks. (if the puddles commonly noted under their parked aircraft were any indication)
In the civilian bizjet world, (where battle damage is of somewhat less concern) MIL-PRF-5606G is still commonly used on many types.