Engine Flashcards
What controls engines
Dual channel FADEC system
What type of engines
General Electric
Cf34- 8E5
High bypass dual rotor turbofan
Describe how fuel gets to engines
From collector tanks to engine fuel pumps. Splits into 2 streams
High pressure pump back to tanks to supply motive flow
Low pressure pump to heat exchanger to fuel filter, back to high pressure pump then to FMU (fuel metering unit) then to fuel imjectors
Oil system lubricates and cools what ?
Turbine engine main shaft bearings and accessory gear box
Where is oil quantity info displayed
MFD
What does the starter system include
ATS ( air turbine starter)
SCV ( starter control valve) controlled by FADEC
Describe start sequence on ground
FADEC opens SCV to allow pneumatic system to provide air to the ATS. FADEC initiates ignition at 7% N2 and fuel flow starts at 20% n2 provided ITT is 120° c or less
After lightoff , starter cutout at 50%n2 and commands FMU TO accelerate to ground idle
Ignition system
How many systems for start are energized
Ground?
Flight?
1 on ground
2 in flight
What does ignition override do
Both igniters on each engine are energized
Will cause sig reduction in igniter life if used frequently
Describe in flight cross bleed start
Identical to ground start except FMU opens to provide fuel after 15 seconds even if 20% n2 is not reached
Describe windmilling start
Commanded by start stop switch
Ignition at 7 % n2
Fuel flow at 7.2% N2 or 15 seconds whichever occurs first
Does FADEC provide protection for hot starts/ hung or failure to light off
On ground yes. If no lightoff in 15 seconds after fuel flow it switches ignitions
In flight- no
When do you abort start
If no lightoff within 30 sec of fuel flow
Describe auto relight
FADEC monitors n2 and turns on both igniters and schedules relight fuel flow in event if flameout
WML icon will show next to respective engine n2 on EICAS
Inflight If engine does not relight automatically within 30 sec or n2 falls below 7.2% you should-
Consider it a failed attempt and you should terminate it manually by moving start stop switch to stop position
Auto relight on ground is terminated and fuel flow is shutoff if
N2 falls below 52%.
Thrust reversers are —- actuated
And controlled via
Hydraulically
Thrust lever
What prevents inadvertent thrust reverser deployment and stowing
An interlock controlled by FADEC
Consisting of 2 actuator locks and an independent cowl lock
What is the purpose of the cowl lock
Prevents inadvertent thrust reverser deployment
Describe thrust reverser deployment
On ground move thrust levers to idle rev thrust
Once both cowls are deployed you can command Max rev thrust by holding thrust levers in Max rev
What happens if one reverser fails while in Max rev?
Operating reverser will provide only min rev thrust unless you select just the operating thrust lever to Max rev
If thrust reverser actuates in flight what happens
Engine thrust is limited to idle thrust
Engine control system consists of
FADEC
Thrust levers
T2
N1 sensors
What does thrust lever do
Receives input of desired thrust setting from pilot or auto throttles
What does T2 do
Monitors engine inlet air temp for FADEC control calculations
What does n1 sensor do
Provides fan speed info for FADEC and airplane vibration monitoring system
Describe FADEC
Main component of engine system It provides Engine protection Control of requested and Max N1 Control of ATTCS
FADEC has 2 identical independent channels one is the in control
Channel the other is always in standby in case of active channel failure
The channels switch control on every start
Where does FADEC get it’s electrical power
Below 50% n2 from the airplanes electrical system
Above 50% n2 from the PMA ( permanent magnet alternator)
Describe the ATTCS
Automatic takeoff thrust control system,
Controlled by FADEC and is available on t/o and go around
It will provide RSV Power in event of engine failure
Displayed on EICAS as white - armed
And green - engaged. ( only when thrust levers are in TOGA
When will RSV POWER BE ACTIVATED
ATTCS must be engaged
And if one of the following occurs
N1 difference greater than 15%
One engine fails during takeoff
One engine fails during go around
Windshear detected
Max thrust commanded by thrust levers
What is minimum flex thrust for takeoff
75% of Max rated takeoff thrust or
Climb -2 + .5 %n1 whichever is higher
What does
TO-x mean
Thrust used for normal takeoff
What are the different idle modes
Flight idle
Approach idle
Final approach idle
Ground idle
When is approach idle activated
Alt less than 15000’
In flight
Flaps 1 or greater
Gear down
When is final approach idle active
Alt lower than 1200 agl
Landing flaps set
Gear down
Describe n2 over speed protection
Whenever n2 reaches 102% FADEC commands an engine shutdown
In the event of 3 consecutive over speed indications within 30 sec FADEC will not relight the engine
If FADEC aborts the start due to a high ITT what do you need to do
Close the SCV by putting the start stop switch to stop
How much oil does each engine hold
- 5 quarts
7. 2 usable
How much oil does APU hold
4.54 quarts
