Engines/APU Flashcards
Thrust Reference Modes
Takeoff:
- TO
- TO 1
- TO 2
- D-TO
- D-TO 1
- D-TO 2
Climb:
- CLB
- CLB 1
- CLB 2
Continuous:
- CON
- CON 1
- CON 2
Cruise:
- CRZ
- CRZ 1
- CRZ 2
Other:
- GA
- MAN
EGT Start Limit Line
Displayed (Red) prior to and during engine start until engine is stabilized
When is the Inflight start envelope displayed
- respective Fire Switch in
- Fuel Control switch is in CUT OFF
- N2 RPM(N3-RR) is below idle
- Primary and Secondary EICAS displayed
Secondary EICAS engine indications
- N2 RPM
- Fuel flow (FF)
- Oil pressure
- Oil temperature
- Oil quantity
- Vibration
Engine vibration indication sources
N1
N2
BB - source is unknown and average vibration is displayed
When does the Standby Engine Indicator (SEI) in view?
In AUTO:
- AC Power is lost
- EICAS display failed
Selected ON
Engine Start Valve light illuminated (amber)
- start valve not in commanded position
- N2 RPM exceeds 50% and starter valve open
Engine Start Selector positions
GND
- Opens Start Valve
- arms selected ignitors
- selector magnetically held in GND position until 50% N2
AUTO
- closes start valve
- terminates ignition
- selected ignitors operate continuously when slats extended or engine Anti-ice ON
OFF
- no ignition
CON
- selected ignitors operate continuously (no time limit)
FLT
- Both ignitors operate continuously (no time limit) regardless of selector position
EEC Power Switch
NORM - Aircraft power provided to EEC when engine is not running
ALTN - Permanent magnet alternator (PMA) selected to provide power to EEC when engine is running
APU Fault Light
- APU has automatically shutdown
* APU fuel valve disagrees with the commanded position
APU Selector in the OFF position
- Closes APU bleed air valve, if open
- Initiates APU cooling cycle
- Closes the APU fuel valve and inlet door shutting down APU when cooling cycle is complete
- Resets auto shutdown fault logic
Engine description (PW)
- 2 x Pratt and Whitney PW2037
- 37,000 lbs of takeoff thrust
- two-rotor axial flow turbofans of high compression and bypass ratio
- N1 Rotor —> Fan, low pressure compressor, low pressure turbine
- N2 Rotor —> high pressure compressor, high pressure turbine
- N2 Rotor drive accessory gear box
Primary Engine Indications (PW)
- EPR
- N1
- EGT
What determines max EPR value?
- Electric Engine Control (EEC), or
- Thrust management computer (TMC)
*EPR varies with existing ambient conditions
Reduced takeoff trust ratings
TO 1 - approx 91% of takeoff thrust
TO 2 - approx 81% of takeoff thrust
How is Assumed Temperature Takeoff thrust calculated
- Thrust Management Computer (TMC) calculated the reference EPR(N1 - 767)
- temp entered via TMSP or CDU TO Ref page
- limited to 25% reduction of takeoff thrust or selected climb thrust
Reduced Climb Thrust rating
CLB 1 - approx 92% of max climb thrust
CLB 2 - approx 85% of max climb thrust (noise abatement reduced thrust level)
Purpose of EECs
- electronic engine control
- dual channel (primary and secondary)
- set thrust by controlling EPR based on thrust lever position
- powered by respective engine PMA when engine is running
When does EEC switch from Primary to Secondary Control mode?
- Primary can set thrust using EPR, N1, or N2 control mode
- Secondary can only use N1 or N2 control mode
- automatic switching occurs when primary mode becomes incapable of maintaining control
- automatic switching also occurs when engine shutdown inflight
How can you determine EEC has switched from EPR to N1 control mode
- EPR display blanks
- small thrust increase
N2 Control Mode
- EEC operation in EPR or N1 not possible
- ENG LIM PROT illuminates
- automatic thrust limit protection is not available
- inflight idle speed between both engines may be different
- EGT and rotor speeds must be monitor during reverse thrust operation
L or R ENG STATOR EICAS message
- both channels of EEC are unable to control stator vane actuator
- if engine fails and messages remain displayed engine restart is not possible
Engine Overspeed Protection
- EEC provides N1 and N2 red line Overspeed protection
- If N1 or N2 approaches overspeed, EEC commands reduced fuel flow
- no EGT overtemp protection
Engine Start Sequence (PW)
- ENG START selector to GND:
- opens start valve
- engages air driven starter (connected to N2 rotor)
- closes engine bleed valve
- FUEL CONTROL switch to RUN as N2 accelerated to Maximum motoring speed (less than 1% in 5 sec)
- opens spar and engine fuel valves
- activate selected ignition (normally one ignitors for grnd start and two for inflight starts)
- at approx 50% N2
- ENG START selector moves to AUTO
- starter cuts out and start valve closes
- engine bleed valve opens
