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131 Cards in this Set
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To meet the requirement for precise control of engine parameters ... was developed .
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Electronic Engine Control
EEC |
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2 types of EEC :
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* Supervisory
* Full-authority |
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Major components @ supervisory EEC
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1. The electronic control itself
2. The hydro-mech fuel control @ engine 3. The bleed air & variable stator vane control |
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The hydromechanical element
@ a supervisory EEC controls ..... . |
* Basic engine operations
1. Starting 2. Acceleration 3. Acceleration 4. Shutdown * Also 1. N2 speed 2. Compressor stator vane angles 3. Engine bleed system |
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EEC, acting in a supervisory capacity :
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1. modulates the engine fuel flow
> to maintain the designated thrust (compensates for chx @ flight/ env. cond.) 2. limits engine operating speed & Temp > ensuring safe operation |
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EEC supervisory problem
What happens ? |
1. Control auto to hydro-mech
2. Warning signal @ cockpit |
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Pilot action
@ EEC supervisory problem |
no immediate action is required
(can revert to H.mech any time!) |
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@ supervisory EEC
Automatic Operation EEC receives signals from : (7) |
1. Power Management Switch
2. Engine inlet Px & T 3. Ambient Px 4. ADC inputs > Pitot/ static Px - TAT 5. Engine RPMs – N1 & N2 6. Power lever position > via potentiometer 7. Failure signals |
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@ supervisory EEC
Automatic Operation EEC output command signals : |
* Adjust and control
1. The hydro-mech FCU > via stepper motor > adjusts the throttle metering valve. 2. Ignition circuits. 3. Bleed valves 4. Torque gauge |
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Power Management Switch,
enables .... to be selected (4) |
1. Take off thrust
2. Maximum continuous thrust 3. Climb thrust 4. Cruise thrust settings |
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HMU is acronym for ...
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hydro-mechanical unit
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The HMU is supplied by ...
and provides ... . |
* the HP fuel pump
* the required fuel quantity to the nozzles |
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A HMU redundancy
for the case of EEC failure |
HMU being mechanically connected
to the power lever |
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@ supervisory EEC
Automatic Operation Fuel control is provided by ... & managed by ... , ensuring ...... |
* HMU
* EEC * no surge/ flame out @ accel / decel |
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The HMU comprises:
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1. A stepper motor controlled by EEC
2. A lever > controls fuel shutoff 3. A lever > controls fuel flow |
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Fuel flow supplied to the nozzles
is mainly obtained through two valves : |
1. Bypass valve
2. Metering valve. |
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The fuel
* enters the HMU from ... * with a ... flow. * This flow is split by ... into two flows, > one for the ... via ... > and one ... . |
* pump outlet
* constant * the bypass valve * nozzles * the metering valve * bypass return flow to the pump |
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@ HMU
The position of the bypass valve is a function of ... caused by ... |
the loss of fuel Px
the metering valve |
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@ HMU
The metering valve is ... actuated using a ... the reference pressure being ... , i.e. .... |
* pneumatically
* bellows device * the HP comp outlet Px * P3 |
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@ HMU
The pneumatic servo block is managed * in normal operation by ... * in manual operation, by ... . |
the EEC
the power input lever |
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@ HMU
Normal operation (EEC mode) EEC controls a ... located in ... , regulating ... & thus modulating the fuel flow as requested. |
stepper motor
the HMU Py pressure |
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@ HMU
Manual Operation (Manual Mode), Py Px is regulated by .... |
* simultaneous actions of
> the NH speed governor * connected to the power lever |
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@ HMU
* What happens when Transferring from the EEC Mode to the Manual Mode ? * A ... in the HMU selects the ... instead of ... |
* manual operation > auto connected
* solenoid * manual cam * the EEC cam |
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@ HMU
What happens in case of failure of the EEC ? |
position of the stepper motor is "frozen"
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NH speed @ HMU in the fail mode
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* inc of power
> NH speed remains unchanged > spring load inc * dec of power > NH speed decreases > > spring load dec |
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FADEC is acronyme for .... .
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full Authority Digital Engine Control
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FADEC replaces ... .
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the hydro- mechanical fuel control systems
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Benefits of FADEC:
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1. reduced weight > hence fuel consumption.
2. Automation > reduced pilot workload 3. Optimized engine control 4. Optimized airflow control (near surge op) |
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Parts of FADEC system
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1. Sensors
2. A Central Processor Unit > (EEC or an ECU) 3. A Hydro Mechanical Unit (HMU) |
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FADEC system inputs:
1. Analogue signals from ... . 2. Digital signals from ... . 3. ... . 4. ... . 5. Feedback signals from ... . |
1. electrical sensors
2. aircraft computers (ADC, TMC, FMC) 3. Thrust lever signals 4. Pressure inputs 5. any moving mechanical device |
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@ FADEC
Thrust lever signals are transmitted by ... . |
Rotational Variable
Differential Transformers (RVDTs) |
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Digital signals @ FADED system
are usually on ... Data Bus |
an ARINC 429
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Engine Control Unit (ECU) @ FADEC.
is a ... that computes ... based on ... & ... and then commands the ... to take appropriate actions. |
* dual channel processor
* all functions of the FADEC system * its inputs / stored data * HMU |
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@ FADEC
The HMU provides an interface between the ... and .. . |
* electrical analogue output from the ECU
* the fuel |
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@ FADEC
The HMU functions by ... actuating a ... , thus controlling ... . |
* an Electrical Hydraulic Servo Valve (EHSV)
* Fuel Metering Valve (FMV) * fuel supply to the burners |
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EHSV is acronym for ...
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Electrical Hydraulic Servo Valve
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FMV is acronym for ...
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Fuel Metering Valve
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all hardware within an ECU container is partitioned into ... .
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the two channels
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An ECU @ FADEC system is normally mounted on ... .
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the fan casing
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The Dual Channel architecture of ECU @ a FADEC system allows for ... preventing ....
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> Dual Input,
> dual outputs > and auto switching > from one channel to the other * eliminate any dormant failure. |
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The ECU @ FADEC system
will always select the ... as the Active channel based on a ... . |
“healthiest” channel
fault priority list |
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During engine run status,
each channel within the ECU will determine whether to be in the active state or standby state every ... . |
30 milliseconds
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If the two channels @ a FACEC ECU have equal health statuses, the channels will ..... .
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* alternate Active/Standby status
* on each engine shutdown |
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Assuming the opposite channel @ a FADEC ECU
is of equal or greater health, channel Active/Standby transfer will occur after ... and subsequently ... . |
* the engine has been run above 76% N2
* shutdown (N2 less than 35%) |
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All ... inputs to the FADEC system are duplicated.
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command
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@ FADEC
Only some ... used for... are single |
* secondary parameters
* monitoring and indicating |
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@ FADEC
parameters are exchanged between the two control channels via the ... . |
cross channel data link
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Pressure inputs @ FADEC
Pressure tappings from the engine are plumbed ... into the ECU, either ... or ... and then ... . |
* directly
* discretely to each channel * a single tapping that is split within the ECU * sent to discrete channel transducers |
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Information exchanged
between aircraft computers and the ECU is transmitted over ... . However signals are ... where a computer is not used |
* digital data buses
* hardwired directly from the aircraft |
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The ECU is equipped with BITE,
which provides ... & ... via a ... mounted component called ... (Airbus) or ... (Boeing). |
* maintenance information
* test capabilities * aircraft * MCDU * PIMU |
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The ECU performs a ... on power up, and ... during operation.
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self-test
self monitors |
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@ ECU
operation of a ground test switch .... . |
* powers up the ECU
* and hence a real time ground test |
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For Boeing airframes the ECU stores faults in the ... until ... , when the faults are streamed to a ...
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* ECU volatile memory
* the aircraft lands * Propulsion Interface Monitoring Unit (PIMU) |
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PIMU is acronym for ... .
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Propulsion Interface Monitoring Unit
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No. of PIMUs for engines ?
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one for each
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@ ECU
The PIMU holds the fault until ... . ... will advise maintenance staff to carry out this procedure |
* a BITE test is carried out
* An EICAS message |
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AIRBUS faults will be stored in the ... in ... .
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MCDU
real time |
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@ ECU
BITE interrogation is ... and cannot be covered in a generic FADEC publication. |
airframe specific
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Using the BITE system,
the ECU can ... in ... and hence allows ... from ... to the ... . |
detect and isolate failures
real time switching of engine control the faulty channel healthy one |
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@ ECU
If a standby channel is faulty and the channel in control is unable to ensure one engine function, ... (what will happen?) |
this control is moved to a fail-safe position.
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To perform all its tasks the ECU interfaces with ... ,
either .. or ... . |
* aircraft computers
* directly * via the Engine Interface Monitoring Unit (EIMU) |
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EIMU is acronym for ... .
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Engine Interface Monitoring Unit
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The ECU has a ... limit protection section
comprising max limits for ... and in addition |
* dual channel
* N1 N2 and N3 (RR only) * Compressor Delivery Pressure(Ps3) |
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@ ECU
Thrust regulation on high bypass engine is calculated using ... to calculate the ... to provide the commanded thrust. |
ADC inputs
required fuel |
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thrust is measured in terms of ... or ...
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N1 speed
EPR (RR Trent) > if fail : back to N1 |
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@ ECU
Thrust Regulation As a back up there is ... located within ... . |
* a mechanical Hi-Px compressor (HP2/ HP3) governor
* the HMU |
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* Thrust Control Modes
> CF6 FADEC Control Modes If ADC signal is lost then the ECU will ... . |
use the opposite channel signal
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* Thrust Control Modes
> CF6 FADEC Control Modes If channels inputs do not agree as to which signal is accurate then the ECU will ... using ... . This is also known as the ... . |
* revert to an "alternate" mode
* the last known ambient pressure signal * soft reversionary mode |
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* Thrust Control Modes
> CF6 FADEC Control Modes The soft reversionary mode can cause ... as the other engine is ... . |
* throttle stagger
* still operating in the normal mode |
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* Thrust Control Modes
> CF6 FADEC Control Modes To prevent throttle stagger, the ... for ... , to select ... . |
* ECU mode switches can be pushed
* both engines * hard reversionary mode |
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* Thrust Control Modes
> CF6 FADEC Control Modes Hard reversionary mode means the engines are using ... . |
the fixed cornerpoint ambient temperature
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* Thrust Control Modes
> CF6 FADEC Control Modes When selecting hard reversionary mode Because ... may be higher than cornerpoint > danger of ... the engine > So ... before selecting |
T-amb
over-boosting throttle back |
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* Thrust Control Modes
> R.R. Trent FADEC Control Modes The primary thrust control loop uses ... . If computation is imposible, .... |
EPR
ECU reverts to the N1 mode |
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* Thrust Control Modes
> R.R. Trent FADEC Control Modes In the N1 mode ... is no longer available. |
Auto Throttle
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* Thrust Control Modes
> CFM 56 FADEC Control Modes The engine operates in one of 3 thrust modes : |
AUTO
MEMO MANUAL |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes Entering/exiting the 3 modes is controlled by ... . |
inputs to the Engine Interface Unit (EIU)
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EIU is acronym for ... .
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Engine Interface Unit
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* Thrust Control Modes
> CFM 56 FADEC Control Modes The auto thrust mode is only available between ... and ... when the aircraft is in ... . |
idle
Max Climb Thrust flight |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ Auto Thrust Mode After take-off the throttle is pulled back to ... , the auto thrust system will be active and the Automatic Flight system will provide ... . |
the max climb position
an N1 target |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ Memo Mode is entered ... , from Auto mode if ... . |
automatically
the N1 target is invalid |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ Memo Mode One of the ... is activated. Auto thrust is disconnected by the ... . |
* instinctive disconnect buttons @ throttle
* EIU |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ memo mode, the ... is frozen to the ... and will remain frozen until ... , or ... . |
* thrust
* last actual N1 value * the throttle lever is moved manually * auto thrust is reset |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ Manual Thrust Mode Entered ... (when) |
* any time the conditions
for Auto or Memo are not present |
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* Thrust Control Modes
> CFM 56 FADEC Control Modes @ Manual Thrust Mode Thrust is a function of ... . |
throttle lever position
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What powers the ECU ?
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A dual coil Permanent Magnet Alternator
driven from the External or Accessory Gearbox |
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PMA is acronym for ... .
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Permanent Magnet Alternator
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The PMA can provide all power requirements of an ECU once the engine is running above ... .
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15% N2
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Power back up for ECU
also for ground testing |
aircraft 28V DC
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28V DC is applied to the ECU when
(3) |
1. The start switch > activated
2. The Fuel switch > placed to on (in-flight windmilling start) 3. When ground test power is applied |
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AC supplies 115V AC 400HZ power source
to each ECU channel for ignition excitor # 1 and ignition excitor # 2. The inputs are routed to the exciters or terminated within the ECU by switching relays. |
nothing !
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if the ECU has a double channel failure then the engine will not start because ... .
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the exciters can only be powered via the ECU
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Primary outputs from the ECU are
directed to ...* of ... . and to ...* controlling the ... . |
** the torque motors
* the EHSVs located on the HMU *primary fuel metering valve |
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The fuel metering subsystem is completely contained in the ... .
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HMU
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The HMU is mounted on ... of the ... .
and driven by ... connection to the ... . |
* the front, right side
* accessory gearbox * a mechanical * gearbox |
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The HMU responds to ... from the ECU
to ... for combustion and to ... to operate the engine air systems. |
electrical signals
meter fuel flow modulate servo fuel flow |
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The HMU also receives signals from the aircraft fuel control system to control ... .
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an internal
High Pressure fuel Shutoff Valve (HPSOV) |
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There are ...(No.) ... for electrical interfaces
with the aircraft and ECU. |
* four
* external electrical connectors |
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...(No.) fuel ports connect the HMU with
the ... and ... . |
Four
fuel pump fuel nozzles |
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@ HMU
There are ...(No.) ... for control interfaces with the engine fuel and air systems. |
* 5
* hydraulic connections |
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@ HMU
Each hydraulic interface is controlled by ... that varies ... in response to EEC signals. |
* an electro-hydraulic servo valve (EHSV)
* servo fuel pressure |
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The fuel connections to HMU :
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*Fuel inlet > from fuel pump
*Fuel discharge > to fuel nozzles *Fuel bypass discharge > to fuel pump *Servo fuel inlet > from servo fuel heater |
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The hydraulic connections from HMU :
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*Servo fuel Px > to LP turbine case cooling (LPTCC) valve
*Servo fuel Px > to HP turbine case cooling (HPTCC) valve *Servo fuel reference Px > to LPTCC and HPTCC valves *Servo fuel Px > to the variable bypass valves (VBVs) *Servo fuel Px > to the variable stator vanes (VSVs) |
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The electrical connections to HMU :
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*Fuel control sig > from EEC channel A
*Fuel control sig > from EEC channel B *HPSOV solenoid inputs > from fuel control valves *HPSOV position indication outputs > to the EEC |
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The HMU has ... hydraulic circuits.
They are ... . |
* 3
• A fuel metering circuit • A bypass circuit • A servo control circuit |
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The fuel metering circuit @ HMU
controls ... to the ... in the engine combustor. |
fuel flow
fuel nozzles |
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The fuel metering circuit @ HMU
has a ... and a ... . |
* fuel metering valve (FMV)
* High Pressure fuel Shutoff Valve (HPSOV) |
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@ The fuel metering circuit @ HMU :
Unmetered fuel from the fuel pump goes to ... . |
the fuel metering valve FMV
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@ The fuel metering circuit @ HMU :
Metered fuel from the FMV goes to ... . |
the HPSOV
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@ The fuel metering circuit @ HMU :
If the HPSOV is open, metered fuel is routed to ... . |
the fuel nozzles
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The bypass circuit @ HMU is composed of ......... .
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* a bypass valve,
* a differential Px (delta P) regulator, * and an overspeed governor |
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@ HMU
Fuel pump supplies more fuel than needed for the metered fuel flow. The ... returns excess fuel to the fuel pump. |
bypass circuit
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The servo control circuit @ HMU
... the fuel supply from ... into ... . They operate ... located ... . |
* divides
* the servo fuel heater * regulated & unregulated servo flows * actuators * both inside and outside of the HMU |
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The servo control circuit @ HMU
has a ... section and ... . One : supplies ... for ... and. The other: ... to ... . |
* servo regulating and distribution
* five electro-magnetic servo valves * servo pressure > FMV control * control pressure > engine air system actuators |
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Fuel Metering Valve
is controlled by ... . which itself has ... , one for each ... . |
* the fuel metering valve EHSV
* two coils * EEC channel |
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The FMV has two ... :
which are excited by, and provides a position feedback signal to, each EEC channel |
position-indicating resolvers
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BITE is acronym for ... .
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Built In Test Equipment
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ECAM is acronym for ... .
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Electronic Centralized Aircraft Monitoring
(Airbus version) |
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EICAS is acronym for ... .
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Engine Indicating and Crew Alerting System
(Boeing version) |
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HPSOV is acronym for ... .
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High Pressure Shut Off Valve
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HPTCC is acronym for ... .
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High Pressure Turbine Case Cooling
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LVDT is acronym for ... .
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Linear Variable Differential Transformer
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MCDU is acronym for ... .
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Maintenance Display Control Unit
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RACC is acronym for ... .
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Rotor Active Clearance Control
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Po is ... Px
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atm
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Ps3 ... Px
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Compressor Delivery Pressure
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RVDT is acronym for ... .
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Rotary Variable Differential Transformer
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TLA is acronym for ... .
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Thrust (or Throttle) Lever Angle
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TMC is acronym for ... .
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Thrust Management Computer
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TRA is acronym for ... .
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Thrust (or Throttle) Resolver Angle
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VBV is acronym for ... .
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Variable Bleed Valves
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VSV is acronym for ... .
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Variable Stator Vanes
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