What type of fluid is required for the nose oleo?

The correct answer is hydraulic fluid because nose oleo struts, which are part of an aircraft's landing gear system, require hydraulic fluid to operate properly. These struts are designed to absorb the shock of landing and provide stability during ground operations. Hydraulic fluid serves several essential functions: it transmits force, provides damping to minimize oscillations, and maintains the structural integrity of the strut under compression and expansion.

In contrast, brake fluid is specifically formulated for braking systems and operates within that context; using it in an oleo strut would not provide the necessary characteristics for shock absorption and stability. Engine oil is formulated for lubrication and cooling of engine components and is not suitable for use in landing gear systems. Coolant is used primarily in engine cooling systems and has properties that are different from those required for hydraulic applications. Each of these fluids serves distinct purposes, and hydraulic fluid is the only one compatible with the operational needs of a nose oleo strut.