GoJet Airlines CRJ-550 Practice Test

Isolating the hydraulic pump from the system is done by closing the shutoff valve on the line between the pump and the reservoir. When that valve is shut, fluid cannot flow from the reservoir into the pump, so the pump is effectively disconnected from the hydraulic circuit and safe for maintenance. The master switch or a fuse would only affect electrical power to the pump, not the hydraulic path itself, so they do not fully isolate the system. The reservoir cap simply closes the reservoir opening to contamination or fluid loss, but it does not stop flow in the hydraulic lines.