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pump.
1.2.An hydraulic pump is associated with each
engine. These switches allow the crew to
switch an engine pump off. If an engine is
stopped, the corresponding hydraulic
pump is in fault mode.
3.4. In addition, 2 electric pumps can be run to
provide hydraulic pressure even if all
engines are stopped. In standard
configuration, the Blue electric pump is on
and the Yellow electric pump is off.
5. The Power Transfer Unit (PTU) can be
turned off through this switch. The PTU is
detailed later in this section.
When the engines are stopped, the hydraulic
SYSTEMS
Airbus Series Vol.1
(c) 2007 Wilco Publishing www.wilcopub.com - www.FeelThere.com 51
overhead section looks like this :
Power Transfer Unit (PTU)
When only 1 engine is running, it can provide
hydraulic power to the whole system through
the Power Transfer Unit. For example, if engine
1 is stopped, the Green hydraulic circuit is not
pressurized any more and the hydraulic
pressure decreases. When it is lower than a
specific threshold, the PTU activates to transfer
hydraulic pressure from the Yellow circuit to the
Green circuit, allowing all the hydraulic
systems to keep working.
The PTU generates a very typical sound that
the passengers can hear in the cabin.
Note : The PTU does not activate if the parking
brakes are set. This is done to avoid having the
PTU running when the engines are started one
after the other.
HYD Page
The hydraulic system can be monitored on the
HYD SD page.
1. The 3 hydraulic reservoirs, with an arrow
showing the level.
2. The 3 hydraulic pumps. Their status depends
on the pump switches located on the overhead
panel.
3. Engine references, which show the Green
circuit depends on engine 1, and Yellow
depends on engine 2. They are shown in
amber if the corresponding engine is off.
4. The 3 engine pressures, displayed in
pound per square inch (PSI). It turns
amber if the pressure is too low.
5. Yellow electric pump status. The white
triangle appears filled amber if this pump
is turned on through the overhead panel.
6. PTU status shows how the PTU is currently
used, displayed in amber if the PTU is off.
Possible Hydraulic Configurations
In standard configuration, with all engines
running, it appears like this :
If an engine fails and the corresponding
hydraulic circuit pressure drops, the PTU
comes in action to provide the missing
pressure. On this example, engine 1 is stopped
(shown with an amber ‘1’) :
The PTU arrows show that hydraulic pressure
is transferred from the Yellow to the Green
hydraulic circuit and the typical PTU motor
sound can be heard in the cabin.
If the PTU is turned off through the overhead
panel switch, the PTU arrows appear amber
and the Green hydraulic pressure keeps decreasing.
When it reaches a low level, it is
displayed in amber to indicate a potential
danger :
SYSTEMS
Airbus Series Vol.1
52 For Microsoft Flight Simulator use only. Not for use in real aviation.
Alerts & Warnings
A green status message ‘HYD PTU’ appears on
the E/WD when the PTU is active.
FUEL
The fuel system can be controlled through the
FUEL overhead section.
The aircraft has fuel tanks in the wings and in
the center fuselage. For each tank section, 2
fuel pumps are available.
The fuel system manages the fuel
automatically. Fuel is pumped from the center
tank in priority, then from the wing tanks when
the center tank is empty.
1. 2 switches are available for the 2 left fuel pumps.
2. Center fuel pump switches.
3. Right fuel pumps switches.
4. Cross feed switch.
According to the dark cockpit philosophy, no
switch light is visible when everything is OK,
that is when all the fuel pumps are on.
Fuel Pump Usage
The fuel pumps should always be on. If a fuel tank
becomes empty, the corresponding fuel pump
automatically stops. This is a normal situation.
If the crew turns the center pumps off, the fuel
from the center tank can not feed the engines any
more. However, if the crew turns the left or right
pumps off, the engines can still get fuel by gravity
feed.
Warning : If the engines are fed by gravity,
there is a high risk of engine failure at high
altitudes. If the fuel is not pumped out of the
tanks, the altitude increases the risk of
creating an emulsion that will damage the
engines.
Manipulating the fuel pumps may be useful to
reduce a fuel imbalance. If you have much more
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