THRUST REVERSER SYSTEM D/O (3)THRUST REVERSER HYDRAULIC SYSTEMDESCRIPTION & OPERATIONThe thrust reverser is hydraulically supplied by the blue hydraulic systemfor engine 1, and yellow hydraulic system for engine 2. The thrust reverserhydraulic components control hydraulic fluid flow to the primary locksand pivoting door actuators. Control and feedback signals are exchangedwith the engine EEC. The thrust reverser hydraulic components are:- the ICU with built-in Pressure switch,- the DCU.ISOLATION CONTROL UNIT (ICU)The ICU controls the supply of the hydraulic pressure to the thrustreverser system. When the solenoid is energized by the EEC, theisolation valve opens and supplies pressure through the DCU to theSTOW side of the pivoting door actuators. The ICU isolation valvecan also be locked with the MANUAL INHIBIT lever to preventaccidental operation of the thrust reverser during maintenance work.The ICU also includes a pressure switch which is pressurized whenthe isolation valve is open. This actuation of the pressure switch sendsa signal to the EEC indicating that the isolation valve is open and thatsupply pressure is applied to the reverser system.DIRECTION CONTROL UNIT (DCU)The DCU solenoid is energized to deploy the thrust reverser. Whenthe solenoid is energized, the DCU supplies hydraulic pressure to thepivoting door primary locks. The locks open in sequence and afterthe last primary lock is released, return pressure to the DCU movesthe direction control valve to the deploy position. The direction controlvalve controls the pressure to the deploy side of the pivoting dooractuators.