Aircraft Hydraulic Fluids

Aircraft hydraulic fluids fall under various specifications:
Common petroleum-based:

• Mil-H-5606: Mineral base, flammable, fairly low flashpoint, usable from −65 °F (−54 °C) to 275 °F (135 °C), red color
• Mil-H-83282: Synthetic hydrocarbon base, higher flashpoint, self-extinguishing, backward compatible to -5606, red color, rated to −40 °F (−40 °C) degrees.
• Mil-H-87257: A development of -83282 fluid to improve its low temperature viscosity.

Phosphate-ester based:

• BMS 3-11: Skydrol 500B-4, Skydrol LD-4, Skydrol 5 and Exxon HyJetIV-A plus – Typically light purple, not compatible with petroleum-based fluids, will not support combustion.