MIL-PRF-87257 Hydraulic Fluid, Fire Resistant; Low Temperature, Synthetic Hydrocarbon Base, Aircraft And MissileThis specification describes the characteristics and provides the requirements for a synthetic hydrocarbon base hydraulic fluid for use in the -54??C to +200??C temperature range in aircraft and missile hydraulic systems. This hydraulic fluid is identified by NATO Code No. H-538 \(see 6.5\).