State the basic purpose of the TH-57 hydraulic system and identify which control systems receive hydraulic assistance.
Reduces pilot work loads by reducing cyclic and collective control pressures and feedback generated by the main rotor system.
State the major components of the hydraulic system and their functions.
Power Pack: Consists of a 1 pint cooling reservoir, pump, regulating valve (600 ± 50 psi), and a mount for the Nr tach generator. It is driven by the transmission accessory drive-shaft.
Filter: Micronic metal filter with No bypass function. If clogged the red pip pin indicator will pop up.
Pressure Switch: Closes and completes the “HYDRAULIC PRESSURE” caution lithe circuit when the pressure falls bellow 300 psi. The switch opens, turning off the caution light when pressure rises above 400 psi.
Solenoid Valve: (Fail Safe Valve): Spring loaded to the on / open position allowing hydraulic fluid to go to the three servos. Requires 28 vdc to move the valve to the bypass position which direct fluid back to the reservoir instead of going to the servos.
Servos: 2 outboard servos are the cyclic servos, middle is the collective. Used to boost the control inputs.
Identify the components of the power pack and their functions.
Reservoir: Finned for cooling, 1 pint capacity
Pump Section: Pressurizes hydraulic fluid
Pressure Regulator: Regulates hydraulic fluid pressure (600 ± 50 psi)
Nr mounting pad
State the capacity and pressure requirements of the system.
Reservoir Capacity 1 pint(MIL-H-83282 or MIL-H-5606)
System Capacity2.25 pints
System Pressure600 ± 50 psi
Identify the components of the filter and their functions.
Head, Micronic Metal Filter Element, Body: A Red warning button on top of the filter pops when filter is clogged. O cockpit indication other than loss of hydraulic system and “Hydraulic Pressure” caution light. There is No bypass Function so when filter clogs the hydraulic system becomes inoperative.
State the primary indication of filter stoppage and corrective action.
HYDRAUIC PRESSURE light
Increased force required for control movement
Feedback in control