Introduction
The hydraulic power has two independent and identical systems, identified as hydraulic system 1 and hydraulic system 2. They supply constant pressure and variable flow.
The fluid used is the SAE AS1241 Type IV, a fire-resistant phosphate ester-base fluid. The nominal pressure of the systems is 3000 psi (pressure range: 2900 ± 200 psi.).
General Description
The HYDRAULIC POWER includes these subsystems:
MAIN HYDRAULIC SYSTEM
INDICATING
The hydraulic power system supplies pressure for the operation of the following systems:
Rudder.
Aileron.
Spoilers.
Landing gear.
Brakes (normal and emergency).
Nose wheel steering.
Main door.
Thrust reverser actuation (optional).
One engine-driven pump and one standby electrical motor driven pump (EMDP) supply each system. The hydraulic system 1 has a priority valve which isolates the landing gear system.
The flight control services are more important than the landing gear operation.
This priority valve closes only during the landing gear operation, with the electrical-motor-driven pump supplying the system.
Each system has one accumulator. One supplies hydraulic fluid to the landing gear/main door (Sys 1), and the other, to the emergency parking brake (Sys 2).
The electrical motors which drive the hydraulic pumps have a cross electrical supply: the DC Bus 2 supplies the EMDP of system 1, and the DC Bus 1 supplies the EMDP of system 2.
Hydraulic power from systems 1 and 2 supply pressure for the rudder control at the same time. These systems have manual reversion.
Hydraulic assistance is necessary for rudder control in the event of asymmetric thrust (single engine condition). With symmetric thrust the manual reversion is effective. In case of hydraulic power loss, the rudder control system reverts to a damping mode.
Both hydraulic power system 1 and hydraulic power system 2 also supply the two aileron hydraulic power units (PCA). Hydraulic power is necessary for: single engine control (just one of the systems). If a hydraulic power loss occurs, the aileron control goes back to a damping mode.
Hydraulic power is necessary for the spoiler extension and retraction
The inboard spoiler panels, when operated on the ground, has the function of lift dumpers. The outboard panels operate in flight as speed brakes and, on the ground, as lift dumpers. If a power loss occurs, an internal lock keeps the actuator retracted.
Hydraulic power is necessary to retract and extend the landing gear.
Hydraulic power is also necessary to keep the nose landing gear doors closed with the landing gear retracted. The system has an accumulator which keeps the pressure of hydraulic system 1 in approximately 3000 psi during the systems operations. In case of failure in the hydraulic system 1, the free-fall system operates independently by cables to unlock the landing gear which is consequently extended by gravity.
Inboard and outboard brakes operate the four main wheels with antiskid and differential braking functions. The emergency/parking brake uses an accumulator.
The hydraulic actuator of the nose wheel steering uses the system 1 hydraulic power only. If a hydraulic failure occurs, the hydraulic steering unit (PCU) goes back to a shimmy damping mode.
The hydraulic power operates the thrust reverser panels. Any hydraulic failure cancels the thrust reverser operation.
Hydraulic power is necessary only to close the main door. The opening operation of the door is by gravity, controlled by a hydraulic damping mode. When we close hydraulic system 1, an accumulator keeps energy to close the door.
The figure "HYDRAULIC SYSTEM BLOCK DIAGRAM" shows systems 1 and 2.
The figure "HYDRAULIC SYSTEM 1 AND 2 COMPONENTS" shows the location of hydraulic system 1 and 2 components.
Components
MAIN HYDRAULIC SYSTEM.
The primary sources of hydraulic power of systems 1 and 2 are two engine-driven pumps, one for each engine, and two standby pumps driven by electrical motors.
INDICATING.
The "EICAS (Engine Indicating and Crew Alerting System)" display supplies information about system status and malfunctions to flight and maintenance crew.
HYDRAULIC POWER EMB – 170
Introduction
This aircraft is provided with a hydraulic power system designed to supply power sufficient to meet the performance and redundancy requirements of safe flight. Hydraulic power is used to operate the following aircraft systems and components that require high power and accurate control:
Primary Flight Controls
Spoilers
Landing Gear
Nose Wheel Steering
Main Landing Gear Brakes
Thrust Reversers
General Description
The HYDRAULIC POWER includes these subsystems:
MAIN HYDRAULIC POWER)
INDICATING
The aircraft hydraulic power is supplied by three independent hydraulic systems. Systems No. 1 and No. 2 use EDP (Engine Driven Pump) s as a primary source of hydraulic power and an electric pump as a standby source of hydraulic power. System No. 3 has one electric pump for regular use and a second electric pump available for periods of high flow requirements. Electric power is supplied by the engine IDG (Integrated Drive Generator)s. In abnormal conditions the APU (Auxiliary Power Unit) and the RAT (Ram Air Turbine) are available to supply electric power. A PTU (Power Transfer Unit) is available to transfer power between systems in the event of a right engine EDP failure.
The indicating subsystem provides hydraulic power system status information to the flight crew. Temperature, pressure, quantity, and pump status are continuously displayed on the hydraulic synoptic page of the MFD (Multi-Function Display). Abnormal conditions are reported to the flight crew by the CAS (Crew Alerting System) which generates messages, aural tones, and flashing indicators to alert the flight crew.
Components
MAIN HYDRAULIC POWER (29-10)
The main hydraulic-power subsystem function is to supply pressurized, filtered, and temperature controlled hydraulic fluid to these aircraft systems and components:
INDICATING (29-30)
The function of the hydraulic indicating system is to monitor the hydraulic systems. The systems are monitored for temperature, pressure, fluid quantity, firewall SOV (Shutoff Valve) position and supply flow tube conditions. The status of each hydraulic system is individually and continuously displayed on the hydraulic synoptic page of the MFD (Multi-Function Display). Both normal and abnormal conditions are displayed on the MFD. The CAS (Crew Alerting System) generates warning, caution, and advisory messages to alert the flight crew to abnormal hydraulic system conditions.
Operation
The hydraulic power necessary for aircraft operation is supplied by the EDPs when the engines are in operation. Operation of the hydraulic system is essentially automatic with little flight crew intervention required. Abnormal hydraulic system conditions generate system responses that allow continued aircraft operation. Any necessary load shedding is preprogrammed and automatically accomplished.
Training Information Points
Abnormal system operation generates CAS messages for flight crew information and any necessary action.
CAS messages generate related CMC (Central Maintenance Computer) messages for maintenance personnel information.
Use caution when working around the hydraulic power system and the hydraulic power users. The hydraulic systems each operate at rated pressure of 20684 kPa (3000 psi).
The hydraulic power system uses AS1241 synthetic phosphate-esterbased fluid. This hydraulic fluid can cause severe skin irritation and respiratory difficulties. Use protective clothing.
Autor:
Aviation Systems