How do you determine the appropriate type of hydraulic fluid for a specific system?

Consulting the Aircraft Maintenance Manual or instruction plate is the best method for determining the appropriate type of hydraulic fluid for a specific system. The Aircraft Maintenance Manual (AMM) provides detailed specifications, including the type of hydraulic fluid that is compatible with the aircraft's hydraulic system. It is essential to refer to these official documents because they contain critical information that ensures safety and maintains the integrity of the hydraulic system.

The instruction plate, often placed near the hydraulic reservoir or on the aircraft structure, also reflects the manufacturer’s specifications regarding fluid types. Relying on these authoritative sources minimizes the risk of using incorrect fluids that could lead to system failure, incompatibility, or even safety hazards during flight.

Other methods, while they might provide some general information, do not guarantee accuracy. For example, externally examining the lines may give a visual indication of the hydraulic system but cannot provide specific or detailed information about the required fluid. Checking the manufacturer’s website could yield helpful resources, but it may not be the most reliable or immediate source for certain models or configurations. Asking a co-pilot might not offer accurate information, as they may not have the specific knowledge or documentation at hand to make an informed decision regarding the fluid type.