Engine Flashcards
What kind of engines are on the CRJ?
2 General Electric, turbo-fan engines:
CF34-8C5B1
What does FADEC do?
Receives information from thrust levers and other controls to produce the required amount of thrust.
What is Maximum Continuous Thrust?
13,386lbs
Low pressure spool is comprised of?
N1 single stage fan connected to 4-stage low pressure turbine.
High pressure spool connected to what?
N2 10 stage compressor connected to 2 stage high pressure turbine.
How much thrust comes from the core? How much comes from the high bypass air?
20% from core
80% from bypass
How do the thrust reverser work?
They deflect the bypass air forward.
What is FADEC?
Full authority digital engine control
What does FADEC do?
Uses various input signals to maximize engine performance AND
Automates engine control
How does FADEC get it’s power?
Before start: electrical system
N2 greater than 50%: dedicated alternator
Can a FADEC overheat condition be controlled?
No, may need to shut down respective engine.
How many channels does FADEC have?
2
If 1 FADEC channel fails, how will you know?
“L/R FADEC FAULT 1 or 2” status message
If both FADEC channels fail, how will you know?
Primary Page lacks indications from respective engine
“L/R FADEC” caution
N2 Gauge will have a white ARC when?
Wing Anti-Ice is on. Keeping N2 in the GREEN will ensure adequate bleed air for the anti-ice system.
“HOT” on ITT indicates what?
ITT during engine start exceeded 815 degrees celsius
ITT
Inter-turbine temperature
How many probes and where are they that make up the ITT system?
5 probes, Exit of the high-pressure turbine section
How many sensors are there for Vibration Monitoring in each engine?
2, one N1, the other N2
Is N2 vibration displayed?
No, but if N2 vibration exceeds 1.1 MILS “VIB” amber icon will display
Oil pressure gauges are removed whenever oil pressure rises above _________ PSID and are replaced by _________.
25; N1 vibration indicators
Describe how the thrust lever changes engine power.
Thrust lever sends signals to FADEC, FADEC signals FMU and the FMU changes the amount of fuel delivered to the combustion chamber
What will happen if a thrust lever fails?
“THROTTLE 1” Caution
FADEC will remain at last setting until Flaps are extended for the approach.
Where is the thrust lever mode displayed?
Below N1 on the primary EICAS display.
What does MCT mean below N1?
Maximum continuous thrust… Thrust levers are in CLIMB detent and APR is active or the HIGH PWR schedule switch has been selected ON
Where is the N1 needed to obtain the set thrust mode indicated?
Above the digital N1 indication
What is the purpose of a thrust flex takeoff?
Reduces fuel consumption
Better for the engines
APR
Automatic Performance Reserve
What does APR do
Monitors for loss of engine power during takeoff and approach.
When does APR arm?
Takeoff: both N1 reach 8% of N1 takeoff reference for 5 minutes
Approach: automatically when either engine available and: flaps greater than 20 degrees OOORRRR Landing Gear Extended
Manually: MAX POWER detent on thrust levers
if uncommanded APR activation occurs, what will happen?
“APR CMD SET” caution
How do thrust reversers work?
When initiated, hydraulic actuators move translating cowls aft, uncovering cascade vanes which redirect bypass air forward around the exterior of the engine.
What powers the thrust reverser actuators?
Engine 1 = Hydraulic 1
Engine 2 = Hydraulic 2
“REV” icon means what?
Uncomanded thrust reverser activation
When will the thrust reversers deploy?
- System is armed
- Aircraft is on the ground or wheel spin-up exceeds 20 knots
- Thrust reverser levers are pulled
What is the purpose of the Engine synch switch?
Reduces the noise that results from each engine producing different amounts of thrust by syncing N1 or N2 %s
In engine syncing, which engine is being synced to the other?
Left engine is master, right is slaved
What does HIGH PWR SCHEDULE switch do?
Advances thrust to the one engine inoperative power schedule.
Can we use the high power schedule switch?
NO IT IS PROHIBITED. No operational procedures which use of this switch is required.
How many fuel injectors and orifices are there per engine?
18 dual-orifice.
Primary orifice for low power
Both for high power
What does moving the thrust lever to the SHUT OFF position do?
Closes the shutoff valve in the FMU
If the shutoff valve in the FMU fails to close when the thrust lever is moved to SHUT OFF, what can you do to turn off the engine?
Push the ENG FIRE PUSH for the respective engine. This will close the FUEL FEED Shutoff Valve.
If ____, FADEC will ______ to prevent overspeed.
N2 Exceeds 107%; stop fuel flow and activate engine ignition until N2 decreases, then reintroduce fuel flow.
What will FADEC do if 3 or more overspeed conditions are detected within 30 seconds?
Close pressurizing and shutoff valve, resulting in flameout
How is engine oil filled?
From a storage tank in the equipment bay
Where is the oil pressure sensor?
Down stream of oil filter
Where is the oil pressure red range?
0-24 PSI
Where is the oil temperature probe?
Oil reservoir
Where is oil level sensed?
At the oil reservoir
When is a “L OIL LEVEL LO” status message displayed?
When the oil reservoir is:
57% with engine running or
80% with engine not running
How many ignition systems are there per engine?
2: A and B
Where is ignition system A powered from? B?
A from AC ESS BUS
B from BATT BUS through a static inverter
What is required for starter operation?
DC power
pneumatic air
How is engine starting controlled?
L/R ENG START switch lights on the overhead START/IGNITION PANEL
What happens when an engine START switch light is pressed?
Switch Illuminates
FADEC opens the start control valve, which allows air pressure to rotate the air turbine starter, which will drive accessory gear box, which will turn the N2 rotor, status message “L/R ENGINE START” will appear,
Describe the engine start sequence.
Push the START Switchlight
N2 20% - IDLE
N2 50% - START Switchlight extinguishes, status removed
“NO STARTER CUTOUT” indicates what?
The starter fails to disengage during start
FADEC will automatically abort a start if:
Hot or hung start is detected.
Does the FADEC abort starts in flight?
No, the Start abort feature is inhibited
When will the N1 FAN VIB indications appear?
When both engines are running at idle and both engine oil pressures are above 25 PSID
What is a fuel/oil heat exchanger used for?
To warm engine fuel and cool engine oil
What is the purpose of Variable Geometry Vanes and what controls them?
Optimize airflow in the engine to reduce likelihood of a compressor stall and is controlled by FADEC.
Do the stator vanes move?
Yes, they vary position determined by FMU
What is the purpose of the operability valve?
Dumps over pressure that can potentially build up in the later stages of the compressor section in order to prevent stalls/surges.
Why is high pressure fuel at the fuel nozzles important?
High pressure means better atomization means better burn.
What does the STOP button do?
Closes the air turbine starter valve and disengages the starter.
What do the Cone fuel pumps on the fuel page mean?
They are ejector valves and will work whenever the engine is running.
When are the DC electric boost pumps used?
Primarily for engine starting.
What’s the procedure for a hot or hung start?
TMS Q
(T) Thrust - Shutoff
(M) Motor - 90seconds or below 120 degrees
(S) Stop button - press
(Q) QRC
If both channels of an engine’s FADEC fails, what happens?
The engine shuts down.
Can FADEC from the L ENG control the R ENGs FADEC?
No.
When is the only time FADEC channels will be working at the same time?
Overspeed conditions
What is the lowest IDLE power setting?
GROUND IDLE of 62%
Why is landing idle higher than ground idle?
To keep the engine spooled up for potential go-around
When does FADEC alternator take over?
After N2 reaches above 50%
When is the only time all igniters operate at the same time?
When continuous ignition is ON
What do the ACSCs regulate bleed air to?
45PSI +/-3
Can bleed air be 6th and 10th stage? Why or why not?
No. A one-way check valve prevents 10th stage bleed air from entering the 6th stage port. It’s 10th OR 6th.
If CRZ is displayed is that a target value?
No, it’s a maximum value
What is mounted on the engine’s accessory gear box?
- Engine lubrication pumps
- FADEC alternator
- Hydraulic pump
- Engine fuel pump
- IDG
- Air turbine starter
Is there ever a time when both FADEC channels will command the engine simultaneously.
During overspeed situation, both FADEC channels will command the fuel valves to close to bring the speed into the normal range.
Is there ITT protection and subsequent auto-shutdown in flight?
No, because you don’t want to prohibit yourself from getting it restarted.
When will the L/R OIL LEVEL LO status message appear?
When the oil quantity reaches 80% capacity.
APR
Automatic Performance Reserve
Monitors for loss of engine power during takeoff and approach.
When will APR Arm?
Only armed, not activated:
- TAKEOFF:
N1 reaches 8% of its reference value. So if reference value is 88%, APR would arm as the N1 % moves up through 80%
- APPROACH:
Automatically arms when either engine available and:
(A) Flaps greater than 20%
(B) Landing gear extended
- MANUALLY SELECTED (not just armed)
positioning thrust levers to Max Power. Gives both engines APR.
APR will automatically ________ when an engine failure is detected.
Increases thrust in the operative engine.
Difference between EFIS and EICAS.
EFIS is electronic right information system and consists of the PFD and the MFD on both sides.
EICAS is engine indicating and crew alerting system that consists of ED1 and ED2
