Hydraulic Fluids in Aircraft
Hydraulic fluids used in aircraft are relatively thin compared to industrial fluids. They must also be fire resistant, which is critical when the nearest fire department is five miles below, not a few blocks away. Aircraft hydraulic fluids also differ from industrial applications because they must remain at -65° and up to 275° F. At those temperatures water and vegetable-based oil lubricants will freeze or boil. The primary hydraulic fluids used in military and commercial aircraft depend on the particular application and environment: