Skydrol

Skydrol is an advanced fire resistant aviation hydraulic fluid manufactured by Solutia Inc. There are various lines of Skydrol including Skydrol 500B-4, Skydrol LD-4, and Skydrol 5.

Skydrol is made up of a group of chemical additives dissolved into a fire-resistant phosphate ester base stock which inhibits corrosion and prevents erosion damage to servo valves and includes a purple or green dye to ease identification. It has been approved by most airframe manufacturers including Airbus, Boeing and BAE Systems and has been used in their products for over 40 years.