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Concorde top Aft Engineers panel
This section of the engineers panel covers the following;
1. Hydraulics (Green, Yellow and Blue systems)
Click below to find out more
GENERALHydraulic power is provided by three independent systems. There are two main normal systems, called Green andBlue, and a standby system, called Yellow.
Each of these systems is powered by two engine-driven pumps.
Emergency hydraulic power is provided by a ram air turbine.
DESCRIPTION
NORMAL AND STANDBY
Normal and standby generation is provided by six engine-driven pumps. The two Green system pumps are driven by engines 1 and 2, the two Blue system pumps by engines 3 and 4 and the two Yellow system pumps by engines 2 and 4.
Normal pressure of all three hydraulic systems is 4000 psi and, in case of overpressure, a pressure limiter allows amaximum pressure of 4500 psi.
To prevent cavitation of the engine-driven hydraulic pumps the three reservoirs must be pressurised by air. An auxiliary air compressor is provided to ensure that the three reservoirs are pressurised before engine start.
EMERGENCY
Emergency generation is provided by a ram air turbine (RAT). The RAT is a two-bladed propeller whichprovides power to drive two hydraulic pumps in the event of the engine windmilling speed being insufficient toprovide hydraulic and electrical power at subsonic speeds following a four-engine flame out.
GROUND
Ground hydraulic power generation is provided by two electric pumps that can be selected to pressurise the main and standby systems while the aircraft is on the ground.
The maximum delivery pressure and flow of the electrical pumps is less than that of the engine-driven pumps.
Green Hydraulic System
This system supplies power for normal operation of the following services:-
- Engines 1 and 2 air intake ramps and spill doors.
- One ram of each power flight control.
- One ram of each relay jack.
- Artificial feel.
- One tank 11 fuel pump.
- Droop nose and visor.
- Landing gear.
- Main wheel brakes with anti-skid.
- Nosewheel steering.
- The Emergency Electrical Generator hydraulic motor.
This system supplies power for normal operation of the following services:-
- Engine 3 and 4 air intake ramps and spill doors.
- One ram of each power flight control.
- One ram of each relay jack.
- Artificial feel.
- One tank 11 fuel pump.
Blue Hydraulic System
This system supplies power for standby operation of the following services:-
- Engine 1, 2, 3 and 4 air intake ramps and spill doors.
- Flight controls.
- Droop nose and visor lowering.
- Landing gear lowering.
- Main wheel brakes with anti-skid.
- Emergency and parking brakes without anti-skid.
- Nosewheel steering.
Yellow Hydraulic System
AUTOMATIC PROTECTION FOLLOWING SYSTEM FAILURE
In the event of low pressure or a tank low level in Green or Blue systems, a detection system automatically onloads the Yellow system engine driven pumps and changes the hydraulic power supply for the appropriate ramp and spill door actuators from Blue or Green system to Yellow.
In the event of a low level in Yellow system tank, the first low level detection automatically inhibits the Yellow supply to nosewheel steering, normal brakes and if selected the YELLOW/GREEN or YELLOW/BLUE supply to flying controls.
If after the low level cut off of the selected Yellow supply to flying controls occurs and a low pressure exists in the other side of flying controls, there is an automatic change of Yellow supply to power the second failed flying control system.
If a GREEN ONLY or BLUE ONLY selection by the PFCU servo selector has been made and low pressure occurs in the selected system there is an automatic change to power the selected system with Yellow system.
If the flying controls are being powered by a single main hydraulic system after Yellow tanks low level cut-off, and transfer of fluid from the operating system to Yellow tank causes a low pressure in the operating system and Yellow tanks contents to rise above the low level cut-off, it is a design feature that Yellow system pressure will be supplied to both sides of the PFCUs to power the flying controls.
At a second low level, the Yellow supply to the intake spill doors is cut off, but this is overridden during manual inching on Yellow.
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