Why must mineral-based and synthetic-based hydraulic fluids not be mixed?

Mixing mineral-based and synthetic-based hydraulic fluids is undesirable primarily because they do not mix well and can cause system failure. When these two types of fluids are combined, they may form emulsions or separate layers, leading to a loss of lubrication effectiveness and system performance. This incompatibility can cause blockages in filters and lines, resulting in significant hydraulic system issues, including decreased efficiency and potential component damage.

Additionally, the different chemical compositions of these fluids may result in unpredictable behavior within the hydraulic system, complicating operations and maintenance. Maintaining the integrity of the hydraulic fluid is critical for the safety and reliability of aircraft operations, which is why avoiding any mixing of these fluids is essential. This aligns with established practices and standards within aerospace maintenance and operations to ensure maximum performance and safety.