Engines, APU

Question 1

Which engine component keeps the engine within operating parameters and limits maximum thrust?

Answer 1

Electronic Engine Control (EEC)

Question 2

What is the indication an EEC is operating in normal mode?

Answer 2

The EEC switch (aft overhead panel)
-ON (white) normal control mode
-ALTN (amber) not visible

-ALTN (amber)
—auto switch to soft alternate (ON light still visible)
—manually selected to hard alternate (ON light not visible)
*if Hard Alternate mode selected by thrust lever to idle, ON light still visible

Question 3

With the EEC switch showing both ALTN and ON, thrust levers never having been brought to IDLE, what mode is the EEC in?

Answer 3

Soft Alternate Control Mode

Total air pressure data not valid for more than 15 sec.

Uses last valid flight conditions for engine parameters. Mach not available, uses estimated Mach.

Thrust can be less or more than normal (exceedance) if outside air conditions change.

Remains in soft alternate until hard is selected by retarding thrust levers to idle or pressing EEC switch

Question 4

The EECs provide redline protections(s) for which parameters?

Answer 4

N1 and N2 redline over speed protection in both normal and alternate modes

*the EEC does not provide EGT redline exceedance protection, except when starting engines

Question 5

When do the EECs select approach idle minimum thrust?

Answer 5

Approach idle is selected when:
-engine anti-ice selected ON (either engine)
-flaps in landing config

72-79% N2 and will remain til 5 sec after landing for possible go-around. Then ground idle

*in flight, if a fault prevents EEC from receiving flap or anti-ice signals, approach idle selected below 15,000 ft MSL

Question 6

What is indicated by the ENGINE CONTROL (amber) light?

Answer 6

The EEC detects a fault in the Engine Control System that are not dispatchable when:
-engine operating (N2>50%, start lever idle)
-aircraft on ground
—ground speed <80kts prior to takeoff
—approx 30 sec after touchdown

Question 7

What indicates an EGT exceedance after engine shutdown?

Answer 7

A red box displayed around the digital readout indicating an in-flight exceedance has occurred

Question 8

How is an EGT redline exceedance displayed?

Answer 8

The digital readout, box, needle, and indicator are displayed:

-Amber when EGT “in CAUTION” range (exceeding max continuous limit)

-Red when EGT “at/exceeds REDLINE” (max takeoff/continuous/start EGT)

Question 9

What causes the ENG FAIL (amber) alert on the EGT indicator?

Answer 9

When respective engine operating below sustainable idle (50% N2) and Engine Start Lever in IDLE position.

Remains until engine:
-recovers
-Start Lever moved to CUTOFF
-Fire Switch pulled

Question 10

How do you display the fuel used?

Answer 10

FUEL FLOW switch on center forward panel

3 position switch displays:
-RATE: fuel flow to each engine
-USED: fuel used since last reset. After 10 sec reverts to fuel flow
-RESET: fuel used for 1 sec, decrease to 0, then display fuel flow

Question 11

What does the OIL FILTER BYPASS light indicate?

Answer 11

an impending bypass of the associated Scavenge Oil Filter

Remains illuminated until condition no longer exists

Inhibited:
-takeoff >80kts to 400 RA/30 sec whichever first
-landing below 200 RA til 30 sec after touchdown
-periods when flashing inhibited

Question 12

Which position(s) does a start switch need to be in for both igniters to activate in case if engine flameout?

Answer 12

Any Position when a flameout is detected
-rapid uncommanded decrease in N2
—above idle IGN commanded for 30 sec
-N2 below idle rpm
—Gnd below idle, above 50% N2
—Air below idle, above 5% N2

Question 13

During ground starts, which malfunction(s) do the EECs monitor for?

Answer 13

Impending hot starts
Engine stalls
EGT start limit exceedances
Wet starts (after 15 sec)

*EEC turns off ignition and shuts off fuel

Question 14

How is an impending hot start indicated during ground starting?

Answer 14

The white box surrounding the EGT digital readout flashes white

Reset when start lever moved to CUTOFF or engine reaches idle N2

Question 15

What are the reverse thrust indications on the Upper Display above the N1 indicators?

Answer 15

REV amber: related thrust reverser moves from stowed position

REV green: thrust reverser reaches deployed position. Reverse thrust lever can then be moved past detent 1 (idle reverse) to detent 2
*can be pulled beyond detent 2 for max reverse thrust

Question 16

What causes REVERSER (amber) light on the engine panel?

Answer 16

Thrust lever commanded to stow. Extinguishes 10 sec later when Isolation Valve closes
-illuminated more than approx 12 sec, malfunction occurred, ENG and MASTER CAUTION illuminate

*a pause of >16 sec will cause electro-mechanical lock to prevent sleeves from further movement.
*cycling thrust reversers can clear fault and restore operation

Question 17

What does the APU provide?

Answer 17

Bleed air for engine starting or air conditioning.

Auxiliary AC power source

Supplies electrical and pneumatic power to aircraft systems in flight or on ground without external ground equipment.

*burns 220 lbs/hr with electrical load
100 lbs/hr at 39,000 ft no load

Question 18

What will cause automatic shutdown of the APU?

Answer 18

Auto shutdown protection provided for:
-over speed conditions
-low oil pressure
-high oil temp
-APU fire
-Fuel Control Unit failure
-EGT exceedance
-other system faults monitored by ECU

—————————————————————

Auto shutdown with FAULT light:
-fuel SOV not in commanded position
-loss of DC power
-ECU failure
-APU fire
-Inlet door not in commanded position
-APU inlet overheat
-loss of both EGT signals
-no speed signal
-no acceleration
-no APU rotation
-no flame
-generator filter clogged
-high oil temp
-over temp
-reverse flow (load compressor)
-oil temp/inlet temp sensor failure
-underspeed

Auto shutdown with OVER SPEED light:
-Fuel Control Unit Solenoid failure
-loss of over speed protection
-over speed

With LOW OIL PRESSURE light
-low oil press for more than 20 sec

*Placing battery switch to OFF will cause APU to shutdown.

Question 19

Will the APU operate with the Battery Switch OFF?

Answer 19

No. APU will shut down if switch placed off

Question 20

How long should the APU operate after the illumination of the APU GEN OFF BUS (blue) light before using it as a bleed air source?

Answer 20

2 minutes

Allows added time for rotor shroud clearance to open past low clearance point achieved at 100% rpm. Prevents shroud rub. Extends service life.

Question 21

How long should you wait after turning the APU Switch to OFF before positioning the Battery Switch OFF?

Answer 21

2 min (NG) after APU GEN OFF BUS (blue) light extinguishes

Allows adequate time for APU inlet door to fully close.

*3 min (MAX)