Hydraulics Flashcards
How many hydraulic systems are there and what does each system supply
The aircraft is equipped with two independent hydraulic systems, identified as system 1 and system 2. The systems are identical in concept and performance; they differ only in capacity and subsystems supplied. System 1 operates the LH aileron, rudder, elevator, stabilizer, alternate brakes, landing gear, nose-wheel steering, flaps, speed brakes, lift dumpers and thrust reversers. System 2 operates the RH aileron, rudder, elevator, stabilizer, and normal brakes
What items are not affected by failure of a single system
In the event of a single hydraulic system failure, operation of the elevators and rudder is not affected. Aileron control forces will be higher than normal
What pumps are there in each system
The main components for each system are a tank, two engine driven pumps, and one electrically driven pump
When will the tank transfer valve open and what is its purpose
To equalize the fluid level in the tanks on the ground a transfer system is installed. In the fluid transfer line a transfer valve is installed. This valve is normally closed and will open for a pre-set time with the aircraft on the ground, when the parking brake is set and at least one engine is running. To ensure equal air pressure in the tanks, the top of the tanks are interconnected. In the air pressure connection line a shut-off valve is installed. This shut-off valve opens and closes in parallel with the transfer valve
What is normal operating pressure and where is it displayed
3000 psi and it is displayed on the overhead panel
What is the effect on the hydraulic system of pulling the fire handle
When a fire handle is pulled the relevant fire shut off valves close. This will isolate both engine driven pumps from the tank supply
What is the effect on the hydraulic system of failure of an engine
There is no effect if 1 engine fails
In which system is the priority valve and what is its purpose
The priority valve will close if system 1 pressure falls below a pre-set value to ensure that power remains available for the flight controls, speed brakes, and thrust reversers. The valve will open to restore pressure to the landing gear, nose wheel steering, lift dumpers, alternate brakes and flaps when the pressure rises above a pre-set value
When would you use the electric pumps
A low capacity electrically driven pump is installed in each system. Its main purpose is for maintenance system testing. It can also be used to pressurize the brake system prior to engine starting.
What is the minimum system quantity with the system not pressurised
70% of each system
What are the hydraulic alerts and what is their level
Low pressure alert—— level2
Low Qty alert—- level 2
System overheat— level 2
Single pump and hyd tank pressure—- level 1
