Skydrol is a fire resistant hydraulic fluid in accordance with the standards set forth in Aeronautical Material Specifications (AMS) 3150c. These specifications prescribe that the autogenuous^([sic]) ignition temperature of such a fluid must be higher than 750°F. (399°C.), determined in accordance with certain testing procedures. Testing conducted by the manufacturer of Skydrol indicates that the flash point of that fluid is 180°C., the fire point is 215°C., and the autoignition point is 496°C. However, Skydrol exposed to air at elevated temperatures will undergo thermal decomposition and the flash, fire and autoignition temperatures will decrease by as much as 9°C.
Source: wiktionary