Power Plant Flashcards
How many spools are there and how are they designated
It is a twin spool bypass system containing HP spool and LP spool
What does each spool drive
LP spool drives N1
HP spool drives N2
What does the starter drive
The starter drives the HP shaft via the HP gear box
What does the combustion section consist of
The combustion section consist of 10 interconnected liners, each of which incorporates a fuel spray nozzle. The tube type liners are installed in a annular casing. Two igniter plugs are installed per engine.
How is the airflow split up as it passes the engine
The output from the fan is divided into two separate flows. One flow enters the LP and HP compressors to be further compressed before entering the combustion section, where fuel is added and the resultant mixture ignited. The hot gas so generated expands through both the HP and LP turbines. The other flow bypasses the engine core. The fan bypass air stream and LP turbine exhaust are mixed before discharge to the atmosphere through a propelling nozzle which incorporates a two door thrust reverser unit.
What could cause an engine overheat alert
Eng overheat alert is presented if the temperature of the cooling airflow exceeds a preset value
Where is the engine bleed tapped from
Two tappings on the HP compressor provide the bleed air, selection is automatic depending on condition and requirement.
How is engine oil cooled
By a fuel cooled oil cooler
How is IDG oil cooled
IDG oil is cooled by passing IDG oil through a primary air-cooled oil cooler located in the rear by-pass duct and a secondary fuel cooled oil cooler
Is the engine and IDG oil shared
No they are independent
Where is starting air derived from
Air can be supplied to the starter motor by the APU, a ground supply unit, or cross-bleed from a running engine
Describe an engine start
Air is admitted to the starter motor when the electrically operated starter valve is open. The starter valve will open when the engine selector is operated. The starter system is electrically armed and disarmed via the START p/b. Both fuel and ignition are applied when the respective FUEL lever is opened. The starter motor rotates the HP shaft. At a present value of N2, starter cut-out occurs, the starter valve closes. lf the starter valve does not close, an alert will be presented.
When should light up occur in starting
Once the starter is selected on and N2 has stabilised, and the fuel lever is set to open within 10 seconds light up should occur.
What are the starter limits during start Max TGT 740 for 2 secs
Light up within 10 seconds. Total time from starter on to light up within 2 mins
What can you do if a starter valve doesn’t open
lf the starter valve does not open electrically; the valve can be opened manually
What igniter plugs are active and when with the ignition selector in:
CONT 1, CONT 2, AUTO , RELIGHT.
Each engine has two ignition systems installed, system 1 and system 2, to operate the respective igniter plug. One IGNITION selector provides the selection for both engines of system 1, system 2, or both systems simultaneously via the CONT 1, NORM, CONT 2 or RE-LIGHT position of the selector
In the RELIGHT position of the ignition selector, both ignition system 1 and 2 are activated irrespective of START p/b and FUEL lever positions
How is ice prevented from forming in the engine fuel system
Hot oil and oil and fuel heat exchanger
What lever controls the HP fuel valve and what are its positions
The fuel flow regulator is controlled by the thrust lever, which can be operated manually or automatically by the Auto throttle system
By what means may the thrust levers be operated
Manually or automatically by the Auto throttle system
What effect has the flight control lock on the thrust lever movement
When the flight control lock is on the forward thrust lever movement is limited approx 80% of N2
What happens to IDLE RPM on approach
To ensure fast engine acceleration from idle to TOGA thrust is case of a go- around, idle N2 is increased automatically to approx 70 per cent N2 when the gear is down. Approach idle is cancelled approx 5 seconds after touchdown.
What thrust ratings may be selected on the TRP
TOGA and FLEX, climb ,crz
How do you set an assumed temperature for FLX
When scheduling flexible thrust select FLEX at the TRP and check that the EPR target at MFDS is equal to the EPR value for the assumed temperature obtained from the take-off limit table or the Quick Reference Handbook.
What do you need to do to set EPR Manually
Both AFCS Channels failed to both Auto throttle switches pressed manually the EPR can be set manually by means of MAN EPR Selector at the TRP
How are thrust reversers actuated
Hydraulically by System 1
How do you know reversers are operating
When deployed a green R displayed at the top of the EPR tape
Can thrust reversers be used before touchdown
No, only deployed on ground
What happens if a reverser deploys inadvertently
Corresponding thrust lever snaps back to idle
Where are engine indications normally presented
Primary page MCDU
What parameters does the EFSU look at
A dual channel engine failure sensing unit (EFSU) is installed to detect an engine failure. The EFSU receives inputs of N1 and thrust level position from both engines. The EFSU provides for the rapid detection of large thrust loss of one engine during take-off, climb, or cruise when both thrust levers are positioned to above MIN TO. The EFSU provides an engine failure signal to AFCAS, FWC, the air conditioning system and the engine ignition system
What is SEI and where can it be used
The primary engine parameters can also be read from the Standby Engine Indicator (SEI). The SEI is connected directly to the engines and can be switched on/off any time.
How is vibration indicated
Vibration (VIB) is represented by two green tapes for each engine. Each tape represents an engine spool and indicates the actual value above or below a threshold mark. A VIB p/b at the ENGINE panel allows the pilot to verify high vibration levels by selecting alternate sensors.
What does the normal and alternate vibration sensors monitor
Verify high vibration levels in both spool
