HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Welcome to this presentation covering the hydraulic system on A320 Series aircraft.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The aircraft has three continuously operating hydraulic systems. They are designated the green,, blue green blue,, and yellow systems. Each system operates independently. There is no possibility of fluid transfer from one system to another. These systems function at a normal operating pressure of approximately 3000 psi.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
To provide additional redundancy,, each system is redundancy provided with at least two pressure sources, including………..
-- engin engine e driven driven pumps, pumps, -- elect electric ric pumps pumps,, -- a Ram Air Turbine Turbine (RAT), (RAT), -- and a Power Power Transfer Transfer Unit Unit (PTU).
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Each hydraulic system includes a reservoir for fluid storage and recirculation. To prevent pump cavitation, the reservoir is automatically pressurized by the aircraft’s pneumatic system. Normally, High Pressure (HP) air from engine 1 pressurizes the hydraulic reservoirs automatically.
G B Y HYD RESERVOIRS
If the bleed air pressure is too low,, the system takes bleed low air pressure from the crossbleed duct.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
GREEN SYSTEM USERS Let's first take a look at the green hydraulic system. A fire shutoff shutoff valve is positioned upstream of the engine driven pump, enabling the crew to stop the flow of hydraulic fluid to the engine should an engine fire occur. The shutoff valve is closed using the ENG 1 FIRE pb. The primary pressure source for the green system is a hydraulic pump driven by engine 1 (left engine).
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
GREEN SYSTEM USERS The green system includes an accumulator that helps maintain constant pressure by covering transient demands during normal operations. Unlike other components discussed, the green accumulator can neither be monitored nor controlled from the cockpit. This is the only time it will be mentioned.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
GREEN SYSTEM USERS A backup source of pressure for the green system is the Power Transfer Unit (PTU). It is bidirectional and enables: - The yellow system to pressurize the green system or, - Th The e green system to pressurize the yellow system. The PTU activates automatically if the differential pressure between the green and yellow systems is greater than 500 psi. The PTU pressurizes the system with the lower pressure.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
GREEN SYSTEM USERS
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QUIZ
YELLOW SYSTEM USERS
The yellow system includes a reservoir,, fire valve, engine reservoir driven pump (driven by engine 2) and an accumulator, all of which function the same as those in the green system.
An additional backup source of pressure for the yellow system is an electric pump which can be controlled from the cockpit.
E
The electric pump is also used when operating cargo doors. While the electric pump is operating the cargo doors, the only other yellow system devices that can operate are braking and engine 2 reverse.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
GREEN SYSTEM USERS
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QUIZ
YELLOW SYSTEM USERS
The yellow system also includes a hand pump which can be used to provide pressure to operate the cargo doors if the yellow system’s electric pump fails.
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The yellow system hand pump is located on the right side of the fuselage. Operating cargo doors using the hand pump requires two people. One to operate the pump, and the second to operate the door selector (located at each cargo door).
Yellow system hand pump
Cargo door selector
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
GREEN SYSTEM USERS
NORMAL OPERATION
ABNORMAL OPERATION
BLUE SYSTEM USERS
DIFFERENCES
YELLOW SYSTEM USERS
The blue system includes a reservoir and an accumulator accumulator.. It is unique in that its primary pressure source is an electric pump. This electric pump activates automatically after the first engine is started. A pump driven by a Ram Air Turbine (RAT) pressurizes the blue system if normal sources of electrical power are not available.
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The PTU cannot pressurize the blue system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The green green,, blue blue,, and yellow hydraulic systems power ALL of the aircraft’s flight controls and many other aircraft systems. Most aircraft are configured as you see here, however some items such as nosewheel steering are different on some aircraft. This will be discussed in the DIFFERENCES section.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
If a hydraulic system malfunctions, the respective System Display (SD) displays the effected components. In this scenario, we can see which flight control surfaces are effected by a green hydraulic system failure because they are displayed in amber .
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Even more helpful, the STATUS page displays a complete list of the systems and components impacted by the failure. The STATUS page shown here is a good example. Notice the information provided with the loss of the green system. You will have more opportunities to review the STATUS page during the ABNORMAL OPERATION section of this lesson. This concludes the OVERVIEW section of this lesson.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The HYD page displays the green,, blue green blue,, and yellow hydraulic systems from left to right respectively.
We will now examine individual items displayed on the page, starting at the bottom with the reservoirs.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The right facing “ >” indicates the fluid level. It is normally normally green and moves up and down the white vertical index to reflect changes in fluid level. The green “box” at the upper right of the index represents the normal fill range for hydraulic fluid. The crew will check that the hydraulic quantity is within the normal fill range during the preflight. While the hydraulics are operating inflight, it is possible for the hydraulic quantity to be less than the fill range. This is particularly true for the green system after the gear has been retracted. Advance to retract the landing gear and gear and observe the drop in reservoir quantity which occurs after the gear is raised. EXIT TO
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ABNORMAL OPERATION
The indicator is displayed in amber if the quantity drops to within the amber low-level warning “box” on the right side of the index. This would be accompanied by an ECAM caution message.
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
LO AIR PRESS is displayed in amber, and an ECAM message is displayed, if reservoir air pressure drops below normal.
OVHT is displayed in amber, and an ECAM message is displayed, if the hydraulic fluid temperature is above normal.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The fire valves in the green and yellow systems are displayed in-line green when the valve is open (i.e., not fully closed). Cross-line amber indicates the fire valve is fully closed. In this example, engine 2 has been shut down using the ENG 2 FIRE pb. The engine shut down is also indicated by the amber 2. The engine numbers are normally white. They are displayed in amber when an engine is not running.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
One additional point about the fire valves. From this ECAM depiction it would appear that, with the fire valve closed, hydraulic fluid cannot flow beyond that point. In reality, that is NOT true. If the fire valve is closed, hydraulic fluid is allowed to bypass bypa ss the engine engine.. This relationship is simply not displayed on the HYD page. The fluid is available for another pressure source (e.g., PTU or electric pump) to use in order to pressurize the system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Notice that the yellow system engine driven pump now has an amber LO indication. This is because fluid is no longer flowing to the engine driven pump. LO is also displayed if the pump is not performing properly and providing low hydraulic pressure. If the pump is selected OFF OFF,, using a pb on the overhead HYD panel, the indication changes to cross-line amber. When the pb is in its normal on position, and the pump is providing normal pressure, the indication is in-line green.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Notice how the PTU is currently displayed. This PTU indication shows that the PTU, using energy supplied by the green system, is now pressurizing the yellow system. Remember, no fluid Remember, f luid is being transferred. Let's look at some other possible PTU indications.
The PTU is pressurizing the yellow hydraulic system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the PTU is pressurizing the green hydraulic system.
The PTU is pressurizing the green hydraulic system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
DIFFERENCES
In this example, the PTU pb is in AUTO and the PTU is not transferring pressure.
The PTU pb is in AUTO AUTO and the PTU is not transferring pressure.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The PTU is displayed in amber if amber if the PTU pb is OFF or the PTU fails its self test . A PTU self self test is conducted during second engine start. A PTU fault during the self test test is the only time a PTU fault message is generated. It is important to remember that the PTU is unmonitored after the self test is complete. If the PTU fails inflight, there will be no change in the indication. It is unlikely you would be aware of a PTU failure in flight. An amber PTU indication does not always mean it has failed. It generally indicates that the PTU has been selected OFF.
The PTU pb is OFF or the PTU has failed its self test.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Moving on to the electric pumps, the ELEC legend is normally white for both the primary blue electric pump and the backup yellow electric pump. ELEC is displayed in amber if the pump’s normal electrical power supply fails or the pump is selected OFF. An amber OVHT is displayed if the electric pump overheats.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Because of its role as a backup pressure source, the yellow system electric pump is presented in additional ways. In this example, the yellow electric pump is not operating.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the yellow electric pump is ON and providing normal pressure. The pump can be manually selected ON using a pb on the overhead HYD panel. It also activates automatically during cargo door operation with the engines shut down. In that case, the pump only pressurizes a portion of the yellow system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the yellow system electric pump has been activated, either manually or automatically autom atically,, and yellow system pressure is low low.. Also in this example, example, the PTU has been selected OFF by the crew.. This will be discussed crew later in the presentation.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Next, we move on to the backup pressure source for the blue system, the Ram Air Turbine (RAT). The drop-out RAT is coupled to a hydraulic pump that allows the blue system to function if electrical power is lost or both engines fail. The RAT deploys automatically if AC BUS 1 and AC BUS 2 are lost. It can also be deployed manually using a pb on the overhead panel. In addition to providing blue system pressure, the RA RAT T also provides hydraulic pressure to drive an emergency generator if necessary. The emergency generator is discussed in the electrical system lesson.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the RA RAT T is in its normal stowed condition.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the RA RAT T is deployed. If the RA RAT T is not available or fails, it is displayed in amber . The RAT can only be stowed by maintenance personnel when the aircraft is on the ground.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Finally, we come to the system labels and system pressure readings at the top of the HYD page. In this example, all three systems are operating at their normal pressure. If hydraulic system pressure drops below 1450 psi, it is displayed in amber . We now move on to the HYD overhead panel.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The HYD panel is located on the aft center of the overhead panel and allows the crew to control key components of the hydraulic system. It also provides a graphic depiction of the basic layout of essential essen tial system eleme elements. nts.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The two engine driven pump pbs, ENG 1 PUMP and ENG 2 PUMP,, are normally on (lights PUMP out). This allows the pumps to operate when the respective engine is running. If either of these pbs is selected OFF OFF,, the respective engine driven pump is deactivated. Continue for a demonstration. Notice the PTU activates automatically to pressurize the green system.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The PTU pb is normally in the AUTO (lights out) position. This allows the PTU to activate automatically if necessary. Selecting the PTU pb OFF deactivates the PTU. This is done in certain abnormal situations. Let's select the PTU OFF.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The guarded BLUE ELEC PUMP pb is normally in the AUTO (lights out) position. This allows for automatic activation of the blue system’s primary pressure source. If AC power is available, the pump activates automatically after first engine start. If the pb is selected OFF OFF,, the blue electric pump is deactivated. Let's select the BLUE ELEC PUMP pb OFF.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The yellow ELEC PUMP pb is normally off (lights out). With the pb off, the yellow electric pump activates automatically when a ground worker operates the cargo door (if AC power is available). If the pb is selected ON ON,, the yellow electric pump activates (if AC power is available). Either way AC power must be available for the yellow electric pump to function. Let's push the YELLOW ELEC PUMP pb.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
We now move on to discuss the FAULT lights in the pump and PTU pbs. The FAULT lights illuminate if the respective pump malfunctions and is not providing proper pressure. This is the classic example of the Airbus FAULT light philosophy. The FAULT light illuminates to assist in locating the correct pb when performing ECAM action steps. Let's select the ENG 1 PUMP OFF and observe the FAULT light extinguish.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
If a pump (or PTU) pb is selected OFF: -The white OFF light Illuminates. - The respectiv respective e item is deactivated. - Th The e FAULT light extinguishes.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The pump and PTU pb FAULT lights also illuminate if the pumps or PTU are working fine but other system problems require that all system pressure sources be deactivated. These problems include: - Sys System tem reser reservoi voirr overhea overheatt - Sys System tem rese reserv rvoir oir low low air pressure - Sys System tem low flui fluid d level level
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, low air pressure in the green reservoir requires that all green system pressure sources be deactivated. Therefore, even though they have not malfunctioned, FAULT lights in the ENG 1 PUMP and PTU pbs illuminate. Let's select these pbs OFF and observe the FAULT lights extinguish.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
A reservoir reservoir overheat situation is a significant exception. During a reservoir overheat the FAULT lights remain illuminated, even with the pbs selected OFF, until the overheat condition no longer exists.
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HYDRAULICS
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CONTROLS & INDICATORS
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Finally, we discuss the RAT. The primary purpose of the RAT is to pressurize the blue system. The RAT MAN ON pb is used to extend the RAT for hydraulic purposes only. Hydraulic pressure provided by the RAT can also be used to drive an emergency generator. The RAT extends automatically inflight if AC BUS 1 and AC BUS 2 are lost.
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HYDRAULICS
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CONTROLS & INDICATORS
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The purpose of the RA RAT T MAN ON pb panel is to manually extend the RAT to pressurize the blue system without activating the emergency generator. This is only required if the blue electric elect ric pump is is lost and one of the other hydraulic systems has also failed.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this example, the green system has been shut down due to a reservoir overheat and the blue electric pump has also failed. The ECAM has directed that the RAT be extended to pressurize the blue system. Using the RAT MAN ON pb on the HYD panel, extends the RAT to pressurize the blue system. The emergency generator will not be activated. Let's lift the guard and push the RAT MAN ON pb to deploy the RAT for hydraulic purposes only.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The RAT can be extended one of three ways: 1. Automatically due to a loss of AC BUS 1 and 2: • The RAT provides blue hydraulic pressure AND • The hydraulically driven emergency generator activates automatically.
2. Pushing the RA RAT T MAN ON pb on the HYD panel: • The RAT RAT only provi provides des blue hydraulic pressure.
3. Pushing the MAN ON pb on the EMER ELEC PWR panel: • The RAT provides blue hydraulic pressure AND • The hydraulically driven emergency generator activates. That concludes the CONTROLS & INDICATORS section.
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HYDRAULICS
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OVERVIEW
CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
In this section we will discuss the crews interaction with the hydraulic system during normal operations. Because the hydraulic system is fully automatic in normal operation, most of your interaction with the system will occur during your preflight preparations. We’ll begin our discussion with the HYD panel.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The normal configuration of the HYD panel during initial cockpit preparation is lights out. Occasionally, on the first flight Occasionally, of the day, you may see all of the FAULT lights illuminated in the pump and PTU pbs during the early stages of the preflight. This is because the pneumatic “head pressure” on the reservoirs has bled off over time. When APU bleed or another air source supplies the pneumatic system, the FAULT lights should extinguish.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Continuing with the preflight, the crew will verify the fluid levels of all three hydraulic systems using the HYD page. This should be accomplished when the hydraulic systems are static and not in use. Let's push the HYD key on the ECAM control panel. Since neither engine is running, all three systems show zero pressure. The fluid level should within the normal fill range (green “box”). From the previous section you should be able to identify that the yellow system quantity is below the normal fill range. Unless the yellow system is currently operating the cargo doors, you should contact maintenance for assistance.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The yellow system has now been serviced and we are ready to start engines. The ENG page would normally be displayed during engine start. For training training purposes we have displayed the HYD page to see the hydraulic indications. Advance to start engine 2. Engine 2 (right engine) is running. Notice the normal operation of the yellow system. Also notice that the blue system electric pump activates automatically after the first engine is started. The PTU is inhibited at this point, even though there is more than a 500 psi difference between the green and yellow systems, it is not operating.
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You are probably wondering how the PTU is inhibited during engine start? What a great question. On the ground, the PTU is inhibited if the master switches are split (one OFF and one ON) and eithe eitherr the nosewheel steering is disconnec disc onnected ted or the parking brake is ON. In other words, the system knows that you are starting or shutting down engines and the aircraft is being towed or is stopped.
Nosewheel steering disconnected by ground crew
OR
On the ground
Split master switches
Parking brake ON
In that case the green system, and thus the PTU, are not required. The PTU is also inhibited for 40 seconds after the cargo door is operated. More on this later in the lesson.
For 40 seconds after cargo door door operation
PTU inhibited
Advance to start engine 1 and view the HYD page.
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PTU inhibited
HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The moment you commence the second engine start (engine 1), the PTU is no longer inhibited. Sensing a pressure differential of more than 500 psi between the green and yellow systems the PTU automatically activates. This sequence ensures that the PTU is tested prior to e ach flight. An ECAM message is displayed if the PTU fails to operate during its self test. Advance to complete the engine 1 start. With engine 1 running, the PTU deactivates and all three systems operate normally normally..
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CONTROLS & INDICATORS
NORMAL OPERATION
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Remember that the PTU is inhibited for 40 seconds after operation of any cargo door is complete. This ensures that when the yellow electric pump activates for cargo door operation, there is no chance that the PTU can pressurize the green system, which would be a safety issue for ground personnel. If a second engine start is attempted shortly after a cargo door is closed, a PTU FAUL FAULT T may occur. This is because the PTU is inhibited and results in an unsatisfactory self test. The PTU FAUL FAULT T requires accomplishing a reset in accordance with procedure.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Because the hydraulic system is highly automated, you should really have no reason to interact with the system for the remainder of your flight, unless a hydraulic abnormal occurs. We will now move on to the ABNORMAL OPERATION section of this lesson.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
This section presents a sample of abnormals that could be encountered with the hydraulic system. You are inflight. Everything is normal and then this happens….
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
The green system engine driven pump is producing low pressure. Notice that with with a 500 psi differential sensed, the PTU automatically activates to pressurize the green system. Let's push the MASTER CAUT light to extinguish both of them. Now let's accomplish the ECAM action step by pushing the GREEN ENG 1 PUMP pb. Notice the FAULT light assists you in finding it. The green system engine driven pump is now depicted as OFF on the HYD page and the action step is no longer displayed.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Now let's push either CLR key on the ECAM control panel to clear the message from the E/WD. This clears the message and also displays the STATUS page. The STATUS STATUS page displays the green system engine driven pump as the only inoperative system. You would now clear the status page and then consult the FCOM for follow-up information. We will end this scenario at this point. A failure of the yellow system engine driven pump would have a similar outcome. A failure of the blue system electric pump has more significant consequences, as you are about to see.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
A blue electric pump overheat has been detected. We have extinguished the MASTER CAUT lights for you. Let's accomplish the ECAM action step by pushing the BLUE ELEC PUMP pb (after lifting the guard). This action shuts down the blue system.
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HYDRAULICS
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Notice that the action step is removed and has been replaced by a boxed primary failure message indicating the loss of the blue system. The box indicates that the primary failure effects secondary systems.
Boxed Primary Failure(s)
Secondary Failure Messages
The effected secondary system is displayed on the right side of the E/WD. In this example, the flight controls system is effected by the blue system failure.
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HYDRAULICS
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CONTROLS & INDICATORS
NORMAL OPERATION
ABNORMAL OPERATION
Push either CLR key to clear the message. The failure message is removed from the E/WD and the F/CTL page is displayed to show the impact of the loss of the blue syst system em on the flight flight controls. Because of the redundant design of the flight controls system, only spoiler pair 3 is rendered inoperative. Although the blue blue jacks jacks are lost for the ailerons, elevators, and rudder, these flight control surfaces remain operational, powered by other hydraulic systems.
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Push on either CLR key to clear the F/CTL page and display the STATUS page. page . The STATUS page lists the items lost due to the loss of the blue system. It also provides approach procedures and indicates that the slats extend slowly (now powered by only one hydraulic system). It will also be necessary to apply a landing distance multiplier because two spoiler panels are inoperative.
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The FAULT light in the BLUE ELEC PUMP pb is still illuminated. The STATUS page indicates that IF BLUE OVHT OUT the BLUE ELEC PUMP pb may be returned to AUTO. The overheat condition can be monitored using the FAULT light. If the FAULT light extinguishes, the overheat condition no longer exist. Clear the status page then consult the FCOM for follow-up information. We will end this scenario at this point.
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As mentioned earlier, earlier, there are three types of reservoir problems: low fluid level, low air pressure, and overheat. In all three types, the eventual result is shutting down the system with the problem. A low air pressure situation was briefly described earlier in this lesson. Next, we will discuss a green reservoir low level.
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The green reservoir has a low fluid level. We have extinguished the MASTER CAUT lights for you. The PTU has activated to pressurize the green system. However, the ECAM requires that the green system pressure sources be deactivated, including the PTU.
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Let's push the PTU pb on the HYD panel to accomplish the first ECAM action step. The PTU has been shut down, the FAULT light extinguished in the PTU pb, and green system pressure has dropped to zero. Let's push the ENG 1 PUMP pb on the HYD panel to accomplish the next ECAM action step.
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The pump is now shut off and the loss the of green system is now reflected as a boxed primary failure on the E/WD. Secondary failure messages indicating that the flight controls and landing grear (WHEEL) are also impacted by the primary failure.
Boxed Primary Failure(s)
Secondary Failure Messages
With all action steps complete, complete , we will push either CLR key to clear the message and view the F/CTL page.
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You can see on the F/CTL page that two sets of spoilers are lost. Because of system redundancy,, all other flight redundancy control surfaces remain operational. Let’s push a CLR key to view the WHEEL page. Here you see that the autobrakes are inoperative. More on that in the Landing Gear & Brakes lesson. Let’s push a CLR key again to view the STATUS page.
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Here you see an extensive list of various items that are no longer operational because of the loss of the green system. You also see approach procedures associated with this failure. They include the fact that you will be required to gravity extend the landing gear. Since both slats and flaps use green system pressure, and pressure from another hydraulic system to operate, they will both extend at approximately half their normal speed. Let’s clear the STATUS page. You would refer to the FCOM for additional information. We will terminate this scenario at this point.
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Dual hydraulic system failures are extremely rare and subject to many variables which make a complete demonstration of such an abnormal impractical during this presentation. What follows is a single example of a dual failure showing the initial warnings, indications, and systems effected. Here we return to a previous scenario where the green was shut down because of low fluid f luid level. Continue to see what happens if a second system fails.
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A low fluid level has now been detected in the yellow system. You are alerted to this dual hydraulic system failure by flashing MASTER WARN lights and a continuous repetitive chime. We have already cancelled both of them for you. Let's accomplish the first ECAM action step by pushing the YELLOW ENG 2 PUMP pb on the HYD panel. This is as far as we will go with the procedures.
Let's take a closer look at the failure message on the E/WD.
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The serious implications of a dual hydraulic system failure are indicated by a red boxed primary failure message and a red LAND ASAP memo on the right side of the E/WD. This abnormal has a significant impact on the flight controls system as indicated by the remaining failure messages and action steps. You also see that the F/CTL and WHEEL systems pages will be viewed as you clear through this abnormal. Let's now take a look at what the STATUS page will look like when you clear to it.
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A whole whole laundry list list of inoperative components are displayed on the right side. Some of the more significant items include both reversers, the flaps, both autopilots, antiskid, nosewheel steering, and the ability to extend and retract the landing gear normally. All of this has a significant significant impact on the approach including: • Landing FLAPS 3 • Increasing the approach speed • Applying a significant significant landing distance multiplier • Flying the aircraft in direct law when the gear is gravity extended • Braking the aircraft using the alternate system supplied by a special brake accumulator accumulator..
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Here is what the STATUS page will look like with a blue and yellow system failure. Of special note is the requirement to gravity extend the landing gear. Even though the green system is still working, the ECAM directs you to gravity extend the gear to avoid putting a heavy load on the single remaining hydraulic system.
FLAPS
Remember, you must have at Remember, least one functioning hydraulic system to control the aircraft. This completes the ABNORMAL OPERATION section of this lesson.
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Let's take a look at some of the hydraulic system differences.
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The ECAM pages are virtually identical on all aircraft. There are only minor differences in the location of items.
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CRT Style Hydraulic Page
NORMAL OPERATION
ABNORMAL OPERATION
DIFFERENCES
LCD Style Hydraulic Page
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However, there is one big However, difference. On all A319s and and some A321s, the nosewheel nosewheel steering (NWS) is powered by the yellow hydraulic system. On some some A321s the nosewheel steering is powered by the green hydraulic system. Nosewheel steering is covered in the Landing Gear & Brakes lesson. This concludes the DIFFERENCES section.
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Engine 2 is running but the PTU is not pressurizing the green hydraulic system. Why not?
The PTU has been selected OFF.
The PTU can only pressurize the blue system.
The PTU is being inhibited.
The PTU can only pressurize the yellow system.
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Engine 2 is running but the PTU is not pressurizing the green hydraulic system. Why not?
The PTU has been selected OFF.
The PTU can only pressurize the blue system.
The PTU is being inhibited.
The PTU can only pressurize the yellow system.
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You get a HYD G RSVR OVHT message. Why does the ECAM procedure ask you to select the PTU OFF first?
To prevent the hot hydraulic fluid from being transferred to the yellow system.
To depressurize the yellow and green systems.
To prevent the blue system from pressurizing pressurizing the green system.
To stop the t he PTU from pressurizing pr essurizing the green system after you select the ENG1 pump off.
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You get a HYD G RSVR OVHT message. Why does the ECAM procedure ask you to select the PTU OFF first?
To prevent the hot hydraulic fluid from being transferred to the yellow system.
To depressurize the yellow and green systems.
To prevent the blue system from pressurizing pressurizing the green system.
To stop the t he PTU from pressurizing pr essurizing the green system after you select the ENG1 pump off.
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We have done the procedure for you, this is is how the ECAM will look. Why is the green system label in amber?
The ENG 1 pump has been switched off.
The PTU has been switched off.
Green system hydraulics has low pressure.
The green system is still overheated.
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We have done the procedure for you, this is is how the ECAM will look. Why is the green system label in amber?
The ENG 1 pump has been switched off.
The PTU has been switched off.
Green system hydraulics has low pressure.
The green system is still overheated.
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How is the RAT deployed to power the BLUE system ?
Automatically by the BLUE BLUE hydraulic system.
By pushing the BLUE ELEC PUMP pb.
By lifting the cover and pressing the RAT MAN ON pb.
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How is the RAT deployed to power the BLUE system ?
Automatically by the BLUE BLUE hydraulic system.
By pushing the BLUE ELEC PUMP pb.
By lifting the cover and pressing the RAT MAN ON pb.
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Which is the correct indication that the RAT is powering the BLUE system?
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Which is the correct indication that the RAT is powering the BLUE system?
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What is the normal pressure in the hydraulic system?
500 psi. ???
???
1000 psi.
3000 psi.
2000 psi.
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What is the normal pressure in the hydraulic system?
500 psi. ???
???
1000 psi.
3000 psi.
2000 psi.
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During start up, when is the t he BLUE hydraulic system pressurized?
As soon as the PTU is turned on.
As soon as the BLUE electric pump pump is manually turned on.
Automatically after first engine start.
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During start up, when is the t he BLUE hydraulic system pressurized?
As soon as the PTU is turned on.
As soon as the BLUE electric pump pump is manually turned on.
Automatically after first engine start.
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What does the amber PTU indication mean?
The PTU is switched OFF.
The PTU is supplying the GREEN system.
The PTU is supplying the BLUE system.
The PTU has overheated during flight.
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What does the amber PTU indication mean?
The PTU is switched OFF.
The PTU is supplying the GREEN system.
The PTU is supplying the BLUE system.
The PTU has overheated during flight.
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On the hydraulic quantity indicator, what does the amber level indicate?
The warning level.
The reservoir contents.
The normal filling range.
The temperature of the hydraulic fluid.
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On the hydraulic quantity indicator, what does the amber level indicate?
The warning level.
The reservoir contents.
The normal filling range.
The temperature of the hydraulic fluid.
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With reference to the PTU, which statement is correct?
The PTU is bibi-directional. It can transfer pressure between the YELLOW and GREEN systems.
The YELLOW system can supply the BLUE and GREEN systems.
The PTU ONL ONLY Y allows the YELLOW system to pressurize the GREEN system.
The PTU must be manually selected on for it to work.
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With reference to the PTU, which statement is correct?
The PTU is bibi-directional. It can transfer pressure between the YELLOW and GREEN systems.
The YELLOW system can supply the BLUE and GREEN systems.
The PTU ONL ONLY Y allows the YELLOW system to pressurize the GREEN system.
The PTU must be manually selected on for it to work.
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After take off, you raise the landing landing gear. What will the GREEN hydraulic fluid level most likely look like?
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After take off, you raise the landing landing gear. What will the GREEN hydraulic fluid level most likely look like?
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You have completed the Hydraulics lesson.
Click here to exit to the main menu.
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