Hydraulic System - Use of Back Up Sources
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Transcript of Hydraulic System - Use of Back Up Sources
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The hydraulic systemUse of back up power sources
Operational Liaison Meeting
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2The hydraulic system
Summary
Introduction
Why not use the back up power source in all
cases?
Use of PTU
Use of electrical pumps
Use of RAT
Conclusion
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3The hydraulic system
SummaryIn this presentation,
A320 includes A319and A321.
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4The hydraulic system
Introduction All models are fitted with 3 hydraulic systems.
Example: A340
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5The hydraulic system
All models are fitted with 3 hydraulic systems.
Normal operation:
Each system is supplied by one or two engine
driven pump(s) (except blue system on A320 family).
ENG 1 ENG 2
Example: Green
system on A310
Introduction
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6The hydraulic system
Introduction All models are fitted with 3 hydraulic systems.
Normal operation:
Each system is supplied by one or two engine
driven pump(s) (except blue system on A320 family).
Back up:
Each system has one or more back up power
source(s): PTU or RAT or electrical pump.
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If the normal power source fails In some cases the back up automatically takes
over.
Example:
Failure of the yellowengine driven pump
on A320:
The PTU takes over
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If the normal power source fails In some cases, the procedure requests to
activate the back up manually
Example:
Failure of the
blue enginedriven pump on
A310:
The PTU is
manually selected
for approach
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If the normal power source fails In some cases, the system is lost. No back up
is used:
Example:On A340, when the ENG 2 pump fails,
the blue system is lost.
The elecpump is
not used
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If the normal power source fails When do we use the back up power source?
This depends on the type of back up:
PTU
electrical pump
or, RAT.
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If the normal power source fails When do we use the back up power source?
This also depends on the type of failure:
loss of engine driven pump,
overheat,
reservoir low air pressure,
low level
..and on the number of circuits which are
affected.
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12/6612The hydraulic system
Summary
Introduction
Why not use the back up power source in all
cases?
Use of PTU
Use of electrical pumps
Use of RAT
Conclusion
?
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If the normal power source failsWhy notuse the back up power source in all
cases?
On all our models, due to the architecture of
our systems, a single hydraulic failure leadsonly to the loss of some redundancy.
All functions are available.
Therefore, single hydraulic failure is minor,
according to the certification criteria.
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If the normal power source fails The objectives are:
keep the procedures as simple as possible,
keep the logics for automatic operation as
simple as possible,
avoid negative effects.
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Why not use the back up power source? In case of single failure, all flight controls surfaces
(except some spoilers) remain available.
B GG Y
B Y
THS
Elevators
B
G
Y
Rudder
GY GBBG G Y
YY YY BBB BG GG G
Ailerons Ailerons
spoilers spoilers
Example:
A330/A340
B
G
Y
G
slats flaps
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16The hydraulic system
In case of single failure, all flight controls surfaces
(except some spoilers) remain available.
B GG Y
B Y
THS
Elevators
B
G
Y
Rudder
GY GBBG G Y
YY YY BBB BG GG G
Ailerons Ailerons
spoilers spoilers
Example:
A330/A340
Loss of Green
Why not use the back up power source?
B
G
Y
G
slats flaps
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17The hydraulic system
In case of single failure, all flight controls surfaces
(except some spoilers) remain available.
B GG Y
B Y
THS
Elevators
B
G
Y
Rudder
GY GBBG G Y
YY YY BBB BG GG G
Ailerons Ailerons
spoilers spoilers
Example:
A330/A340
Loss of Blue
Why not use the back up power source?
B
G
Y
G
slats flaps
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18The hydraulic system
In case of single failure, all flight controls surfaces
(except some spoilers) remain available.
B GG Y
B Y
THS
Elevators
B
G
Y
Rudder
GY GBBG G Y
YY YY BBB BG GG G
Ailerons Ailerons
spoilers spoilers
Example:
A330/A340
Loss of Yellow
Why not use the back up power source?
B
G
Y
G
slats flaps
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19The hydraulic system
In case of single failure, all flight controls surfaces
(except some spoilers) remain available.
Flaps and slats remain available for approach.
The autopilot remains available.
Why not use the back up power source?
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20The hydraulic system
Summary
Introduction
Why not use the back up power source in all
cases?
Use of PTU Use of electrical pumps
Use of RAT
Conclusion
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21The hydraulic system
When a PTU is available It automatically takes over.
Example:Failure of the yellow
engine driven pump
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22The hydraulic system
Example:
On the opposite,
failure of the green
engine driven pump
When a PTU is available It automatically takes over.
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23The hydraulic system
When a PTU is available It automatically takes over.
In some cases, the procedure requests to
select it off, to avoid damages.
These cases are: reservoir overheat
reservoir low air pressure, with pressure
fluctuations,
low level.In these two cases, the system
can be recovered for approach
through engine driven pumps.
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24The hydraulic system
When a PTU is available It automatically takes over.
It covers the cases of
failure of the engine driven pump, or
engine failure.
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25The hydraulic system
When a PTU is availableWhy does it automatically take over?
Its operation was necessary to avoid the loss of
one elevator in some cases of dual failure
(G+B orY+B). It was not necessary in case of single failure.
However, for simplification, the logic was based
on a single parameter:DP between yellow and green systems.
(so, it is also used in case of single failure)
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26The hydraulic system
The procedure requests to select manually the
PTU for approach
In case of failure
of the blue
engine driven
pump on, or.
When a PTU is available
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27The hydraulic system
The procedure requests to select manually the
PTU for approach
...in case of
failure of the
yellow engine
driven pump .
When a PTU is available
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28The hydraulic system
As on A320, in case of reservoir overheat or
reservoir low air pressure, the system can be
recovered for approach through engine driven
pumps.
It is not recommended to select the PTU ON in
dual hydraulic failure, with green remaining.
This is to avoid to decrease the reliability of the
remaining green system.
When a PTU is available
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29The hydraulic system
Summary
Introduction
Why not use the back up power source in all
cases?
Use of PTU
Use of electrical pumps
Use of RAT
Conclusion
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30The hydraulic system
When an electrical pump is available
Example:On A340, when the ENG 2 pumpfails, the blue system is lost.
The elecpump is
not used
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31The hydraulic system
When an electrical pump is available
Example:On A340, when the ENG 2 pumpfails, the blue system is lost.
The electrical pump is not used to replace the
engine driven pump.
This applies to all three circuits on A330 and
A340.
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32The hydraulic system
Why not use the electrical pump?
A330/A340 engine
driven pump
delivers about 175 litersper minute
A330/A340 electrical
pump
delivers about 35 litersper minute
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33The hydraulic system
Required flow on green system A340
Available with eng pumps
TO climb cruise land
100
200
300
Flight controls
geargear
Flaps/slats
Flaps/slats
L/mindescent
Available with the elec pump
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34The hydraulic system
TO climb cruise land
100
200
300
Flight controls
slats slats
Required flow on blue system A340
Available with eng pumps
Available with the elec pump
descentL/min
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35The hydraulic system
Why not use the electrical pump?Example: control of right outer aileron
In normal operations: P3 is in control
GY
P3S2
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36The hydraulic system
Example: control of right outer aileron
In normal operations: P3 is in control
GY
P3S2
Why not use the electrical pump?
In case of G failure on A330/A340:
S2 takes over.
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37The hydraulic system
Example: control of right outer aileron
In normal operations: P3 is in control
GY
P3S2
If the green pump is started: P3 takes over again.
If the demand exceeds the available flow, the greenpressure fluctuates around low press threshold.
Switchings between S2 and P3 will occur.
This induces some lateral jerks.
P3S2
P3S2P3S2
Why not use the electrical pump?
In case of G failure on A330/A340:
S2 takes over.
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38The hydraulic system
In case of dual failure, some surfaces may be
lost.
B GG Y
B Y
THS
Elevators
B
G
Y
Rudder
GY GBBG G Y
YY YY BBB BG GG G
Ailerons Ailerons
spoilers spoilers
Example:A330/A340
G+Y failed
G
outer outer
right
Why not use the electrical pump?
B
G
Y
Gslats flaps
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39The hydraulic system
Example:In case of G+Y failure:
The right outer aileron is lost
It moves to its zero hinge moment position
G GB Y
Why not use the electrical pump?
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40The hydraulic system
The right outer aileron is lost
It moves to its zero hinge moment position
G GB Y
If the green pressure is recovered through the elec pump: The right outer aileron is recoveredit comes back to normal position
Example:In case of G+Y failure:
Why not use the electrical pump?
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41The hydraulic system
The right outer aileron is lost
It moves to its zero hinge moment position
If the green pressure is recovered through the elec pump: The right outer aileron is recoveredit comes back to normal position
If flight control demand induces green pressure loss:The right outer aileron is lost againIt moves again to its zero hinge moment position
G GB Y
Example:In case of G+Y failure:
Why not use the electrical pump?
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42The hydraulic system
The elec pump is not designed to replace the
engine driven pumps.
On A330/340, its flow is too low and the normal
use of flight controls leads to pressure drops(ECAM warning triggering, computer switchings
and, if two systems are affected, undesirable
surface movements).
It should not be started in flight, except in some
particular situations.
Why not use the electrical pump?
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43The hydraulic system
When are the elec pumps used in flight? On the blue system, the electrical pump is the
normal power source.
The system is designed for that: the demand iscompatible with the delivered flow.
100
Available with the elec pump
TO climb cruise landdescentL/min
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44The hydraulic system
When are the elec pumps used in flight?
In case of dual failure, if the yellowsystem islost due to the failure of the engine driven
pump :
the procedurerequests to
select manually
the yellow
electrical pump.
(As on blue system, thedemand is compatible with
the flow.)
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45The hydraulic system
When are the elec pumps used in flight?
On the green system, if the two engine drivenpumps are lost:
the two electricalpumps can be
manually started
for approach.
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46The hydraulic system
When are the elec pumps used in flight? On A340, on green system:
ENG 1 ENG 4
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47The hydraulic system
When are the elec pumps used in flight? On A340, on green system:
ENG 1 ENG 4
At take off, in case of
failure of ENG1 or 4, the
electrical pump is
automatically started for 25seconds at landing gear
retraction.
Then it stops.
Same on A330, when ENG 1 or 2 fails.
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48The hydraulic system
When are the elec pumps used in flight? On A340, on yellowsystem:
ENG 3
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50The hydraulic system
When are the elec pumps used in flight?
In case of single failure, for spoiler retraction, if
some of them remain extended at the time of
the failure.
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51The hydraulic system
Summary
Introduction
Why not use the back up power source in all
cases?
Use of PTU Use of electrical pumps
Use of RAT
Conclusion
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52The hydraulic system
When do we use the RAT ? The RAT enables to supply:
the yellow system on A300/A310
the blue system on A320 family
the green system on A330/A340.
It is used:
in case of all engine flame out (it is the only
hydraulic source)
in case of dual hydraulic failures.
Use of RAT depends on the failure
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53The hydraulic system
affecting the related system Overheat or
reservoir lowair pressure.
Loss of the
normal power
supply.
Reservoir lowlevel
Do not use the
RAT.
The RAT canbe used.
(system recovered for approach
through normal pump)
On A320:Do not use
the RAT.
On other aircraft:
The RAT can be used.(dedicated fluid reserve)
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54The hydraulic system
When do we use the RAT ?Dual hydraulic failure:
(G+BorB+Y)
RAT MAN ON
is displayed if the bluesystem is lost due to ELEC PUMPLO PR
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55The hydraulic system
When do we use the RAT ?Dual hydraulic failure:
(G+Y or B+Y)
RAT MAN ON
is recommended if the yellow engine driven pump is
failed.
It is recommended only for approach in case ofyellow
system low level.
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56The hydraulic system
When do we use the RAT ?Dual hydraulic failure:
(G+B)
Only in case of dual low level:
The RAT is automatically extended.RAT MAN ON
is displayed for confirmation.
Why?
This is to cover the case of an engine burst
affecting all the hydraulic circuits.
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57The hydraulic system
When do we use the RAT ?Dual hydraulic failure:
(G+B orG+Y)
Only in case of dual low level:
The RAT is automatically extended.RAT MAN ON
is displayed for confirmation.
Why?
This is to cover the case of an engine burst
affecting all the hydraulic circuits.
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58The hydraulic system
When do we use the RAT ?
Dual hydraulic failure:(G+B orG+Y)
In addition, with new FWC standard (K3.2):
CONSIDER RAT MAN USE
is displayed (except in case ofgreen overheat or dual low
level).
Why?
This enables to recover the use of flaps or slats.
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59The hydraulic system
When do we use the RAT ?
A330/A340 engine
driven pump
delivers about 175 litersper minute
A330/A340 RAT
delivers about 80 liters
per minute at 175 kt.
Below this speed, the
flow is reduced.
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60The hydraulic system
When do we use the RAT ? When the RAT is used, to keep the hydraulic
flow demand consistent with the RATperformance:
a rate limitation is introduced:
on the green surfaces on A330/340
on blue surfaces on A320 (not on A319 or A321)
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61The hydraulic system
ConclusionSingle failure:
Automatic operation of PTU (Y orG).
Dual failure:
Manual use ofYellow electrical pump.
Manual use ofRAT.
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62The hydraulic system
ConclusionSingle failure:
Manual use ofgreen electrical pumps for
approach only
manual use of PTUs (B orY) for approach only
Dual failure:
Manual use ofRAT.
Manual use ofgreen electrical pump.
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63The hydraulic system
ConclusionSingle failure:
No permanent use of back up power sources.
Dual failure:.
Automatic use ofRAT in a particular case.
In other cases, no permanent use of back up
power sources.
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64The hydraulic system
ConclusionSingle failure:
No permanent use of back up power sources.
Dual failure:.
Automatic or manual use ofRAT.
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65The hydraulic system
ConclusionIn case of dual failure:
the back up power source is used
provided the failure enables its use (Ex: not incase of overheat)
provided its use is convenient (Ex: nopermanent use of electrical pump on A330/340)
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ConclusionIn case of single failure:
the back up power source is
sometimes used, but
never necessary to maintain the normaloperations.