Powerplant Flashcards
Battery start Consideration on the ground?
If ignition A is picked by the FADEC, it will not be powered( AC ess bus)….
After 15 seconds FADEC SWITCHES TO ignition B
Ign A
ign B. what buses….
Ign A…. AC essential bus
Ign B …. Bat bus
FADEC means?
Full authority digital engine control
Engine failure detected?
N1 speed less than 15% of the set pwr
Recovers when w/i 13 %
Armed for TO?
N1 on BOTH engines within 8% of take off N1 reference
N1 less than 15 % of set pwr on an engine?
Engine failure detected
Apr armed for g/a?
Appch bit met
Gear down
Or
Flaps greater than 20
N1 both engines w/i 8% of takeoff N1 ref?
APR armed for T/O
Operability valve?
Releases excess air pressure
What provides hydraulics for. Operability Valve and Statir vanes?
Pressurized fuel … Provides hydraulics for operability valve and stator vanes
Test
DC pwr AND pneumatics needed for start
DC pwr AND pneumatics needed for start
FADEC system pwrd by
Abv 50%
Blo 50%
Abv 50%. … Gearbox mounted fadec alternator
Blo 50% … Aircraft electrical system
What drives the accessory gearbox
N2 Compressor
accessory gearbox items
3 fluids -engine oil lube pump
- hydraulic pump
- engine fuel pump
2 electric-FADEC
-IDGs
1 AIR..- ATS
How is the operability valve controlled
By the FADEC
Hydraulically actuated by HP fuel
IGN B … Bus?
DC Battery bus
Compressor stall prevented in 2 ways?
Operability valve
VG ( fuel adjusts the stator vanes)
Apr activates when?
Mismatch of 15%
APR PWR INCREASES?
Toga …. APR
CLIMB … MCT
CRUISE .. Proportional increase
Apr armed?
Takeoff?
Landing?
Takeoff.. N1 both engines within 8% of reference value
Landing… Appch bit met
Ldg gear down or
Flaps greater 20
( either eng avail)
Normal takeoff thrust setting
13600
14500 w/apr
What enables N1 sync
Rt eng. N1 must be within 1.5% of the left engine N1
N2 synch is enabled when?
Rt engine N2 is within 2.5% of the left engine N2
FADEC overspeed protection?
N2 greater than 107%
Starter cut out
50%
Ignition a powered by
Ignition b powered by
Ignition A … AC ESS BUS
Ignition B … Batt bus
If ignitor fails
After 15 seconds it switches
Cruise power?
Proportional increase
Max power detent??
APR on both engines
ALSO GREEN SWITCHLIGHT
APR .. TL’s in detent
CLB …… MCT
TOGA… APR
Fuel pressure is used to manipulate what valve to dump excessive air to avoid a compressor stall
Operability valve
Approach bit met for Landing?
Flaps greater than 20
Or
Gear down
How many channels does eachFADEC have?
Two channels.. One active and one monitoring
15% split N1 between engines?
Engine failure detected therefore APR
Continuous ignition?
Both igniters on both engines
VG Compressor linkage?
Only the first four stages
Idle?
Different Idle stages for different phases of flight
Engines?
2 general electric CF34 -8C5
13600 thrust
14510 APR
What provides most of thrust
Bypass air
The VG System is controlled by FADEC and positioned by actuators through a
Mechanical linkage
High pressure fuel from the engine fuel metering unit hydraulically moves the actuators
The operability valve. Is controlled by
FADEC
and hydraulically actuated by high-pressure fuel from the fuel metering unit
Flex power can only be entered when
- Thrust levers are in Idle or shuts off
- Wait on wheels for at least one minute
- Assumed temperature entered is greater than the actual OAT
- Airspeed is less than 65 kts
Assumed temperature can’t be cleared by
-Selecting delete on the FMS CDU
-if the FMS is not available
Select FLX RESET on the EICAS menu page
The starting and ignition systems are controlled by the
FADEC
What is required for starter operation
DC power and pressurized air(pneumatics)
Each independently controlled ignition system consists of
Two ignition exciters into two igniter plugs
Do the ignition systems alternate between A and B with each Successive start?
Yes
What is the start protection function?
On the ground the FADEC prevents engine damage due to either hot or hung starts
Fuel from the collector tanks is supplied to the respective engine fuel pump unit by
A main ejector or an electrical boost pump
What does the fuel oil heat exchanger do
Uses hot engine oil to heat the fuel
Uses cold fuel to cool the engine oil
If an inadvertent thrust reverser deployment ….what happens?
FADEC Will schedule idle thrust
However the pilot must place the thrust reverser in the idle position
20-20-1 mes
When is the FADEC system powered by the aircraft electrical system?
Until N2 reaches 50% RPM
When is the FADEC system powered by the gearbox mounted alternator
Above 50% N2
Cruise —– proportional increase
CLB—–MCT
TOGA—APR
.
Engine failure detected if
N1 speed decreases below 15% of the “SET” power
When will we see APR displayed in the N1 gauge?
If APR is activated by an engine failure
Or
When the thrust Lever is set to the max power detent
Going to Max thrust gives?
APR on both engines
N1 synch is enabled when?
Rt N1 must be within 1.5% of the left N1
N2 sync?
The right engine N2 must be within 2.5 % of the left engine N2
Engine overspeed protection is provided when
N2 exceeds 107%
Sensed by the FADEC
When the wing anti-ice is selected on
N2 indicators will display a partial white band below the green band
IF N2 decreases into the white range, the N2 pointers will turn white
Test
ENGINE OVERSPEED warning
Indicates that N1 or N2 has exceeded redline for more than four seconds
What happens when the oil pressure gauges show normal pressure during engine start
The gauges revert to N1 vibration gauges
Overspeed protection when
N2 exceeds 107%
When will the FADEC quit attempting relights?
If three or more overspeed conditions have been detected within 30 seconds
APR armed when?
TKEOFF? N1 of both engines are within 8 percent of the take off N1 value
APPROACH? Either engine available, flaps greater than 20° or landing gear down
Engine failure detected when
N1 speed of an engine decreases below 15% of the set power
if failure was due to on an N1 mismatch? The failure signal is cleared when the mismatch becomes less than 13%
Which engine is the master engine regarding synchronization
Left engine is the master engine and the right engine will be slaved to it
N1 sync?
Rt within 1.5% of left
N2 sync?
Rt within 7.5 of left
What is required for starter operation
Pressurized air and DC electrical power
N2 VIB?
Indicated as a VIB icon on the respective N2 gauge
N1 vib gauge?
Displayed after engine start when oil pressure is normal and engines are at Idle
How Is engine oil cooled and combustion fuel heated?
The fuel oil heat exchanger
How many ITT probes?
5
What controls The operability valve?
Fuel is used to control and actuate the operability bleed valve
N1sections?
Single stage fan rotor
Four stage low pressure turbine
How much of the air which passes through the engine is bypass there versus core air?
85% of the air is bypass air
15% is core air
The accessory gearbox is driven by the
Driven by the N2 rotor
The variable geometry system changes the position of which stator vanes?
The first four stages of Statorveins
What also helps provide additional bleed air offload in addition to the variable geometry system?
Operability valve
What actuates the variable geometry compressor linkage?
Fuel
What actuates the operability valve?
Fuel
Does the FADEC have its own power source?
Yes
FADEC alternator
FMU fuel metering unit supplies high pressure fuel for actuating?
Operability valve
VG inlet guide vanes
VG Compressor stater vanes
Thrust reverser limitations during landing
75/60
Max reverse thrust not permitted below 75 kias
Idol reverse by 60 kn
Each FADEC has 2 channels..
Alternated on each successive start
Starting sequence?
The starter drives the engine accessory gearbox which in turn drives the engine N2 core section
Where are oil filter impending bypass and chip detector indications provided or seen?
On the engine fault panel in the aft equipment bay
What happens after an engine over speed? (N2 107%)
Overspeed condition is detected
Shut off valve closes stopping fuel flow
Engine flames out
FADEC Detects flame out and turns on ignition
N2 decreases below over speed threshold
Automatic relight occurs
No more than three over speed conditions within what time.
30 seconds.
22-50
What air is to use before the thrust reverser’s?
Bypass air
Both ignition systems are AC?
Yes
When do we move both thrust Levers into the max power detent?
Wind shear recovery
CFIT
Stall recovery
Thrust reverser system is armed when
Switch selected on
Hydraulic pressure available
Thrust reverser deployed in-flight memory item
Affected thrust lever..Confirm and Idle
Flex thrust Can be set?
Thrust levers idle or shut off
WOW1 minute
Assm’d temp greater thanOAT
A/S less than 65 kts
Continuous ignition during flame out?
Yes
Memory Item dual engine failure?
Cont ign
GA mode is armed on appch?
 Landing grear down
Or
Flaps greater than 20
