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N1-Rotor System Components:
- ducted fan
- 3 stage compressor
- 4 stage turbine
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N2-Rotor System Components:
- 9 stage compressor (first 4 stages feature variable stator vanes)
- single stage turbine
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Why are VARIABLE BLEED VALVES installed?
- at low rpm, LP-compressor delivers more air than the HP-compressor can utilize
- bleed excessive air into the fan duct
- increase the engines stall margin
- improve acceleration characterisic
- VBV are closed with T/O thrust set
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duties of 1st and 2nd stage engine fuel pumps
- 1st: positive flow to fuel/oil heat-exchanger
- 2nd: high press. fuel for MEC
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MEC
- meters fuel
- hydromechanical unit using heated servofuel for adjustment of variable stator vanes and -bleed valves
- regulates N2
- influenced by PMC
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Components of Engine Oil System:
- Oil Tank
- engine driven oil pump
- oil filter
- two independent pressure sensors (for oil press. indication and LOW OIL PRESSURE light)
- Scanvenge Pump
- scanvenge filter (OIL FILTER BYPASS light)
- temperature sensor (Oil temp. indication)
- Fuel Oil heat exchanger
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What is Fan air is used for?
- generator cooling
- airconditioning precooler
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Bleed Air from 5th or 9th stage is used for?
- Anti-icing
- Airconditioning
- Pressurization
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Can 5th and 9th stage bleed air be used simultaneously?
- No, when 5th stage bleed air is insufficient for pneumatic users, MODULATING AND S/O-VALVE opens 9th Stage
- reverse flow to 5th Stage is prevented by a Check valve
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How is the Thrust Reverser controlled?
- electrically controlled
- hydraulically operated
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Thrust reverser components:
- 3 hydraulic actuators
- translating sleeves
- blocker doors
- fixed cascade vanes
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Thrust reverser locking mechanism:
- upper actuator is mechanically locked, unlocks hydraulically
- all 3 actuators are synchronized by the SYNCHRONIZING SHAFT, locked by the SYNC LOCK (electrically pwrd)
- AUTO RESTOW CIRCUIT: if other two locks fail: opens isolation valve, commands directional ctrl valve into stow position
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What is need for reverser operation?
- Hydraulic to operate reverser sleeves
- Electric for reverser ctrl
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Where is EGT sensed?
between High- & Low pressure turbine
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Engine Vibration Monitoring system components
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Minimum Engie start Pressure
- 30 PSI at MSL
- (-0,5/1000ft)
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describe engine start sequence:
- start switch GRD
- @25% N2 & N1>0 -> engine start lever IDLE
- (selected igniter starts to work, Eng. and MEC SO-Valve open)
- FUEL VALVE CLOSED light (fwd ovhd) extinguishes
- inital FF can be observed
- Observe EGT-rise with light up
- @45% N2 Engine start switch holding relay deenergized
- start switch returns to OFF
- STARTER VALVE OPEN light (eng. instr. panel) extinguishes
- Igntion terminates
- duct pressure (fwd ovhd) returns to init. value
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Engine Start Switches CONT
- selected igniter(s)
- continuous ignitions
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Engine Start Switches FLT
- both igniters, regardless of ignition sel. sw. pos.
- continuous ignitions
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PMC
- electronic device
- adjusts fuel according to desired power setting
- influences N2
- maintains constant thrust
- nearly constant N1 corresp. to thrust lever angle
- starts operation above 46% N2
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Why are VARIABLE STATOR VANES installed?
- optimum efficiency
- are automatically positioned depending on pwr-setting by MEC
- increase the engines stall margin
- improve acceleration characterisic
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Engine Idle Ctrl
uses air/gnd sensor to switch between low (22%) and high (32%) idle
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What is special with a BATTERY START?
- only when APU inop, no ext pwr available
- no duct pressure indication
- right igniter usable only (pwrd by AC STBY BUS)
- Engine Idle Ctrl off, enige accelerates to high idle
- (will spool down to low idle as soon as first gen on bus)
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fast EGT rise, high FF (500kg/h):
- HOT START, Engine Start Lever CUTOFF
- before reaching limit EGT
- TLB entry if EGT limit busted
- Maint. action req.
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normal FF, no EGT rise after Eng Start Lever placed to IDLE
- WET START, most propable is an ignition failure
- check CBs
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Idle-N1 and/or -N2 not reached, normal FF, EGT rise
- HUNG START, due to less air and normal FF, EGT is higher than normal
- Do not mistake for a HOT START
- Maint. action req.
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How to recognize an Aborted Engine start
- no N1 or n2 rotation
- no EGT ind. within 10 sec thrust lever placed to idle
- EGT rapidly approaching limit
- no oil pressure with enighe stabilized @ IDLE
- ABORTED ENG. START Procedure has to be done if Eng. Start lever has allready been set to IDLE
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PMC light illuminated
- do not attempt T/O with only one PMC light illuminated
- acc. MEL flight possible with both PMCs OFF (lower nose compartement)
- T/o perf. is reduced, use "PMC OFF T/O"-Procedure
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if oil pressure drops into yellow band
- in flight: no action req.
- on gnd: do not attempt T/O with oil press. in yellow
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eng oil temp in yellow band for more than 15min
-> SHUTDOWN
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OIL FILTER BYPASS light illuminated
- may be a hint for defective eng. bearing
- retard thrust lever
- if light remains on -> SHUTDOWN
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High engine Vibration value?
>4.0
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Thrust reverser deployment suspected in flight?
immediate eng. shutdown
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Requirements for eng. start?
- Start air source (>30PSI)
- DC power: starter valve and engine fuel S/O-Valve
- AC power: Igniters
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Engine Starter cycle limits?
- do not exceed 2 min during each attempt
- a minimum of 20s is needed between 1st and 2nd attempt
- a minimum of 3 min is needed between 2nd and 3rd attempt
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Eng Start switch fails to stay in GND, do not attempt to restart until N2 reaches...
20% N2
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Engine Idle Values (N1, N2, EGT)
- N1: 22.8%
- N2: 60.3%
- EGT: ~500°C
- Oil QTY more than 1,5 USG
- positive oil pressure indication
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Engine Idle N1 (GND)?
N1: 22.8%
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Engine EGT after Start?
EGT: ~500°C
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Engine Idle N2 (GND)?
N2: 60.3%
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Engine Idle N1 (FLT)?
- N1: 32%
- (maintained until 4s after TD)
- prevents compressor icing
- expedites reverse thrust
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Normal Engine starting sequence?
2 - 1
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Normal FF after Engine Start?
300-400 kg/h
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