What is a main feature of nonpetroleum base hydraulic fluids like Skydrol?

Nonpetroleum base hydraulic fluids, such as Skydrol, are formulated specifically to be fire-resistant, which is a significant advantage in aerospace applications. The primary characteristic of these fluids is their ability to not support combustion, especially at high temperatures. This feature is crucial because hydraulic systems in aircraft operate under conditions where the risk of fire can be elevated due to the presence of high-pressure hydraulics and the heat generated by mechanical components.

Unlike petroleum-based hydraulic fluids, which can ignite and sustain combustion, nonpetroleum fluids are designed to remain stable and non-flammable in the event of a hydraulic leak or system failure. This fire-resistant property enhances the overall safety of aircraft operations, reducing the risk of fire hazards that could potentially lead to catastrophic accidents.

In contrast, options that suggest these fluids support combustion or are flammable under normal conditions do not accurately reflect their properties and intended uses in aviation, as safety and fire resistance are primary design considerations for such hydraulic fluids.