Hydraulic machinery failures are commonly caused by misalignment of the system components and by __________.

Correct Answer: Option D — hydraulic fluid contamination

Hydraulic fluid contamination is the leading cause of system failure. Particulates can score precision-machined surfaces, clog orifices, and cause valves to stick. Maintaining fluid cleanliness is critical for the longevity of pumps, motors, and actuators, as required by standard marine maintenance practices for hydraulic systems.