Engines, APU Flashcards
What engines are used on the 737-800?
CFM56-7.
Which rotor is the starter motor connected to?
The N2 Rotor.
When does the EEC become energised during a battery start?
When N2 exceeds 15%.
How does the EEC conduct a self-check during engine start?
It alternates between each of its control channels.
What are the two EEC alternate modes?
Soft and Hard.
When will Soft Alternate Mode enter Hard Alternate Mode?
(i) Retarding the thrust lever to idle.
Or;
(ii) Manually selecting ALTN on the EEC switch.
What does Soft Alternate mode aim to achieve, and how?
It aims to prevent any immediate changes in engine thrust by using the last valid flight conditions to define engine parameters.
When will BOTH the ALTN light and ON indication both remain visible on the EEC?
When the EEC has automatically switched to Soft Alternate Mode.
What are the 3 idle modes that can be selected by the EEC?
Ground, Flight & Approach idle.
Under what conditions is Approach Idle selected by the EEC?
(i) Flaps in landing configuration.
Or;
(ii) Engine Anti-Ice is ON for either engine.
What is the benefit of the higher % RPM in Approach idle than Flight idle?
Improved engine acceleration in the event of a go-around.
When will Approach idle automatically begin, if a fault prevents the EEC from receiving flap or anti-ice signals?
Below 19,000ft AMSL.
What does the EEC meter fuel through?
The Hydro Mechanical Unit (HMU).
How is the oil cooled?
By engine fuel when passing through the oil cooler.
FCOC - Fuel Cooled Oil Cooler.
How is the starter motor powered?
Bleed air.
What gearbox does the starter use to rotate the N2 compressor during start?
The accessory gearbox.
What is the starter cutout speed?
56% N2.
What conditions will trigger ENG FAIL to be indicated on the EGT display?
(i) When the engine is operating at <50% N2; and
(ii) The engine start lever is in IDLE.
What removes the ENG FAIL indication?
(i) Engine recovery; or
(ii) Engine start lever moved to CUTOFF; or
(iii) Engine Fire Switch is pulled.
What will be the first alternate mode the EEC will change to in the event that normal mode fails?
Soft Alternate Mode.
Is thrust protection provided in Hard Alternate mode?
No.
When will the ON indication go blank on the EEC?
When ALTN is selected manually.
What stages is Bleed Air drawn from?
5th and 9th Stage Compressors.
What are the two shutoff valves that fuel travels past before reaching the engine?
(1) Spar Fuel Shutoff Valve
(2) Engine Fuel Shutoff Valve
When will both fuel shutoff valves close?
(i) Start lever is in CUTOFF; or
(ii) Engine Fire Switch is out.
After retarding the thrust levers to idle to enter Hard Alternate Mode, what will be the indications on the EEC switches?
Both the ON and ALTN switches will still be illuminated.
When the engine start switch is selected to GRD, what valves become active?
The bleed air valve closes, and the start valve opens.
Which filter will the engine oil bypass if the filter becomes contaminated?
Scavenge filter.
Are sensors for the oil temperature, oil pressure and LOW OIL PRESSURE located upstream or downstream of the oil pumps?
Downstream.
