The Type dimension of the Aviation Hydraulic Fluids market is dominated by three principal chemistries: synthetic, mineral‑based, and fire‑resistant formulations. Synthetic fluids, typically polyalpha‑olefin (PAO) blends, command the largest share—approximately 45% of total revenue—due to their superior thermal stability, low volatility, and compatibility with modern high‑performance actuators. Mineral‑based fluids, derived from refined petroleum, account for roughly 30% of the market; they remain prevalent in legacy aircraft because of lower upfront costs and established certification pathways, though their performance envelope is narrower. The remaining 25% is captured by fire‑resistant fluids, such as phosphate‑ester or water‑glycol mixtures, which are mandated for aircraft operating in high‑risk environments or meeting stringent safety regulations. Each type contributes distinct cost structures, lifecycle maintenance requirements, and regulatory compliance burdens, collectively shaping the overall market size and influencing OEM sourcing strategies across commercial and military aviation segments.