Engines, APU

Question 1

What engines are used on the 737-800?

Answer 1

CFM56-7.

Question 2

Which rotor is the starter motor connected to?

Answer 2

The N2 Rotor.

Question 3

When does the EEC become energised during a battery start?

Answer 3

When N2 exceeds 15%.

Question 4

How does the EEC conduct a self-check during engine start?

Answer 4

It alternates between each of its control channels.

Question 5

What are the two EEC alternate modes?

Answer 5

Soft and Hard.

Question 6

When will Soft Alternate Mode enter Hard Alternate Mode?

Answer 6

(i) Retarding the thrust lever to idle.
Or;
(ii) Manually selecting ALTN on the EEC switch.

Question 7

What does Soft Alternate mode aim to achieve, and how?

Answer 7

It aims to prevent any immediate changes in engine thrust by using the last valid flight conditions to define engine parameters.

Question 8

When will BOTH the ALTN light and ON indication both remain visible on the EEC?

Answer 8

When the EEC has automatically switched to Soft Alternate Mode.

Question 9

What are the 3 idle modes that can be selected by the EEC?

Answer 9

Ground, Flight & Approach idle.

Question 10

Under what conditions is Approach Idle selected by the EEC?

Answer 10

(i) Flaps in landing configuration.
Or;
(ii) Engine Anti-Ice is ON for either engine.

Question 11

What is the benefit of the higher % RPM in Approach idle than Flight idle?

Answer 11

Improved engine acceleration in the event of a go-around.

Question 12

When will Approach idle automatically begin, if a fault prevents the EEC from receiving flap or anti-ice signals?

Answer 12

Below 19,000ft AMSL.

Question 13

What does the EEC meter fuel through?

Answer 13

The Hydro Mechanical Unit (HMU).

Question 14

How is the oil cooled?

Answer 14

By engine fuel when passing through the oil cooler.

FCOC - Fuel Cooled Oil Cooler.

Question 15

How is the starter motor powered?

Answer 15

Bleed air.

Question 16

What gearbox does the starter use to rotate the N2 compressor during start?

Answer 16

The accessory gearbox.

Question 17

What is the starter cutout speed?

Answer 17

56% N2.

Question 18

What conditions will trigger ENG FAIL to be indicated on the EGT display?

Answer 18

(i) When the engine is operating at <50% N2; and

(ii) The engine start lever is in IDLE.

Question 19

What removes the ENG FAIL indication?

Answer 19

(i) Engine recovery; or
(ii) Engine start lever moved to CUTOFF; or
(iii) Engine Fire Switch is pulled.

Question 20

What will be the first alternate mode the EEC will change to in the event that normal mode fails?

Answer 20

Soft Alternate Mode.

Question 21

Is thrust protection provided in Hard Alternate mode?

Answer 21

No.

Question 22

When will the ON indication go blank on the EEC?

Answer 22

When ALTN is selected manually.

Question 23

What stages is Bleed Air drawn from?

Answer 23

5th and 9th Stage Compressors.

Question 24

What are the two shutoff valves that fuel travels past before reaching the engine?

Answer 24

(1) Spar Fuel Shutoff Valve

(2) Engine Fuel Shutoff Valve

Question 25

When will both fuel shutoff valves close?

Answer 25

(i) Start lever is in CUTOFF; or

(ii) Engine Fire Switch is out.

Question 26

After retarding the thrust levers to idle to enter Hard Alternate Mode, what will be the indications on the EEC switches?

Answer 26

Both the ON and ALTN switches will still be illuminated.

Question 27

When the engine start switch is selected to GRD, what valves become active?

Answer 27

The bleed air valve closes, and the start valve opens.

Question 28

Which filter will the engine oil bypass if the filter becomes contaminated?

Answer 28

Scavenge filter.

Question 29

Are sensors for the oil temperature, oil pressure and LOW OIL PRESSURE located upstream or downstream of the oil pumps?

Answer 29

Downstream.