System Flashcards
Explain CFM56-7 engine?
dual rotor
axial flow turbofan
N1 = fan, LP com, LP turbine
N2 - HP com, HP turbine,
N1 and N2 mechanically independent
N2 rotor drives engine gearboxes
Bleed air powered started motor connected to N2 rotor.
Dual channel EEC regulates engine.
EEC monitor A/T and crew inputs
Primary engine indications?
N1 and EGT
EEC not powered?
N1, N2, oil quantity , eng vibration displayed directly from engine sensors.
Battery start with no power on A/C?
N1, N2 m Oil quantity available.
EEC power only when?
Eng acc to speed >15% N2.
15% EEC energized and pointers/digits for all parameters displayed.
ENG FAIL in amber on EGT gauge?
condition below sustainable N2, 50%.
ESL IDLE
Explain LEAP-1B engine?
Explain EEC
full authority digital EEC
2 independent control channels
auto transfer if one fails
EEC alternate between starts
TL inputs for forward and Rev thrust
N1 to set thrust in 2 control modes - normal and alternate.
Manual selection of mode possible
EEC NORMAL MODE
EEC - sensed flight conditions and bleed air demand to calculate N1 thrust ratings. EEC compares commanded N1 vs actual N1 and adjust FF to achieve commanded N1.
Full rated To thrust?
available at TL position less forward stop.
Fixed/ATM derate TO thrust available?
TL position less than full rated TO
MAximum rater thrust?
forward stop
Two alt modes?
soft and hard
Auto change to soft alt mode?
required signals not available
Indication of soft alt mode?
ALTN switch illuminates
ON indication remains visible
Explain soft alternate mode?
EEC uses last valid flight conditions to define engine parameters - mode change occur with no immediate change in engine thrust
Soft alternate mode - too less/too much thrust?
yes, ambient conditions change
Soft alternate mode remains until?
hard alt mode entered by:
1) retard TL to idle
2) manual select ALTN with EEC
HARD ALTN mode thrust schedule?
thrust always equal to or greater than normal mode
EEC limiting?
N/A n hard alternate mode.
Max rated thrust be reached at TL position less than full forward.
Loss of either DEU?
loss of signal to both EEC’s
EEC ALTN light illuminate
EEC revert alternate mode
Prevent engines - operating single source of data.
Avoid overboost withEEC in HARD alt mode?
hrust lever advance to/near full forward only emergency with terrain
Explain LEAP-1B engine?
in SOFT ALT mode, the Hard alt mode entered, with TL idle?
ALTN ON
ON remains visible.
ON will go off when ALTN is selected manually.
Takeoff Bump Thrust?
increased thrust needed for TO, above normal max TO thrust setting.
The applied thrust rating for GA thrust.
NOT applied to Max Cont or climb thrust ratings.
Structural limit protection?
EEC N1/N2 protection in NORMAL and ALTN modes.
No EGT protection.
Idle operation?
EEC auto sets:
ground min, flight min, app idle
Approach IDLE when?
EAI ON
<19000ft MSL and L or right gear down and locked
<19000ft MSL L or R flaps 15 or more.
Why this higher rpm for same airspeed and alt?
improves engine acceleration time if GA.
Fault prevents EEC from getting flap or gear position signals?
APP idle begin below 19000ft.
MAX - Thrust control malfunction accommodation? TMCA
EEC function - protection against idle thrust asymmetry conditions on ground(RTO or landing roll) Each engine monitored independently.
TCMA the EEC command shutdown?
a/c ground and
TL idle and
engine above idle speed and not decelerating normally.
After TCMA activation, ENG FAIL alert when N2 below ground N2 idle speed.
Explain LEAP-1B engine?
Electronic Overspeed System (EOS)
EEC function
protection - exceedance of engine structural design limit. Uncontrollable N2 overspeed condition in flight - EEC shuts off fuel flow to engine. Amber ENG FAIL N2 below N2 idle speed. THRUST may appear depending on flight condition, power setting and ENG FAIL timing.
MAX - type idles?
Ground MIn
Flight MIn
Icing IDle
App Idle
Icing idle?
Flaps up
Main gear Not down/locked
EAI on
Icing mode, EEC transition?
Min flight idle at 30400ft, increase idle in descent - full icing idle at/below 22000ft.
Approach idle selected?
Flaps 15 of greater
any time flaps not up and EAI ON.
Icing idle vs app idle?
Given airspeed and Alt the N1/N2 higher for icing idle than app idle.
Same condition, app idle vs min flight idle?
App idle higher than flight min idle.
Purpose of Icing idle / Bleed?
Icing idle required to meet bleed demand for EAI system.
Purpose App idle?
Improves Eng acc with GA.
Idle setting vs Flap vs EAI table?
Engine Fuel system explain?
Purpose HMU>
meters the fuel
Name 2 shutoff valves?
FUEL SPAR SHUTOFF VALVE
ENGINE FUEL SHUTOFF VALVE
Where is FF measured?
after the engine shutoff valve
Engine oil system explain?
Purpose oil?
lubricate engine bearings and acc gearbox.
Sensors oil temp indicator, oil press, and LOW OIL PRESS location?
downstream of oil pump prior to engine lubrication.
Engine and fuel indications sensed by EEC, except?
oil quantity
engine valve closed
GRD, Eng start switch uses which power to close engine bleed air valve and open start valve?
BATTERY
engine start, EGT rise before fuel flow?
Initial fuel flow lag actual fuel flow by 2s.
Explain NG vs MAX start?
BRM?
straightens the N1 and N2 rotor shafts
BRM active?
6-90s
BRM indications?
MOTORING
18-24% N2
When is TCMA and EOS test?
ESL move to IDLE, EEC does test.
Test indications?
FF zero.
Engine fuel shutoff valve open/close repeatedly. ENG VALVE CLOSED light illuminate and remain bright blue during logic test, will then extinguish when test complete.
Ground start protection?
HOT start
engine stalls
EGT limits
wet starts
Impending hot start or compressor stall start?
White box surrounding EGT readout flashes white.
EEC software?
7.B.Q
EGT exceeds start limit?
EGT display, box and dial turn RED
Wet start?
EEC turns off ignition and shuts off fuel to engine, 15s after start level moved to idle.
Each engine igniters?
2
Igniter get power from?
L - AC transfer bus
R - AC Standby bus
Auto relight?
flameout
EEc detects flameout - BOTH igniters active
Flameout detected?
rapid drop in N2
N2 below idle rpm
2 ways to start inflight?
Windmill
crossbleed
INFLIGHT start protection?
none
Low oil quantity at low N2 why?
oil scavenge pump not enough pressure to return oil to tank
X-BLD / XB indication based on?
alt
speed
N2
Inflight start red lines explain? NG
only EGT redline - inflight limit
BOTH egt redline and egt start limit - start limit is the EGT start limit for engine start.
Max inflight start?
EEC detects EGT within 10C of START LIMIT REDLINE - interrupts FF and ignition for 1s. then resumes - EEC repeats this - until successful start or start attemp aborted by crew.
Thrust reverser - 3 main components?
Translating sleeve
Blocker door
cascade vanes
TR can be deployed?
RA less 10ft
air/grnd safety sensor ground mode
RT selected to deployment of reverser system explain?
RT select
electro mechanical lock release
isolation valve opens
TR control valve moves to deploy position, allow HYD press to unlock and deploy the reverser system.
Interlock mechanism?
restricts movement of Rev thrust lever until reverser sleeve approached the deploy position.
Amber REV?
reverser sleeve move from stowed position.
TR at deployed position?
Green REV, lever can be raised to detent 2.
Reverser light ON/OFF?
On when TR commanded to stow.
extinguish 10s later when isolation valve closes.
Reverser light on more 12s - malfunction, MCAUT and ENG.
Detent 1 to stow - pause=MCAUT and ENG. 16s pause?
engages elec mechanical lock - prevents TR sleeves from movement. Cycling TR may clear fault.
What inhibits motion to each reverser sleeve?
electro mechanical lock
Hyd operated locking actuator
Auto restow circuit?
compares actual reverser sleeve position and commanded reverser position.
Incomplete stowage or uncommanded movement of Rev sleeves - auto restow circuit opens isolation valve and commands the control valve to stow position, directing HYD press to stow rev sleeves. Auto restow circuit active - isolation valve remains open and control valve held in stowed position untill TR commanded to deploy or maint.
AVM System?
engine vibration levels.
low/high pressure rotor sync vibration.
balance low press rotor
APU cooling?
Cooling inlet above apu exhaust outlet. Circulates through APU compartment, oil cooler and vents at exhaust duct
Elec power to start APU?
AC TBUS 1 or Bat
APU start sequence?
switch momentary START.
air inlet door open
door full open
start sequence begins
proper speed reached
ignition + fuel added
APU ready to accept bleed or elec load - APU GEN OFF BUS on
APU protective shutdown - 3 indications?
Fault
Overspeed
Low Oil press
What controls APU speed through EFC?
ECU
Speed or EGT exceed levels providing elec load?
Elec load is shed.
Elec load and bleed load raise EGT during engine start?
elec load first then bleed shed
Other phases of flight?
Inlet guide vanes closed, reduce Bleed air extraction.
APU Load shedding?
galley and main busses
IFE busses
NO auto restoration of power - manually reset CAN/UTIL
MAX - APU inlet door 3 positions?
closed
flight open 17deg
ground open 45deg
