What are the disadvantages of hydraulics system?

DISADVANTAGES

Hydraulic fluid is highly corrosive to most of the aircraft materials.

Due to the heavy loads experienced in a typical hydraulic system, structural integrity is a must which also means higher structural weight for the aircraft in addition to the weight of its hydraulic lines, pumps, reservoirs, filters, & etc.

Hydraulic system is susceptible to contaminations & foreign object damage (FOD).

Mishandling and constant exposure to hydraulic fluid and its gas fumes without proper equipment and precautions is a health risk.

If disposed improperly, a hydraulic fluid is an environmental risk.