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FCOM System Description > 7. Engines, APU > Flashcards

7. Engines, APU Flashcards

1
Q

A/T LIM Indication

A
  • The FMC is not providing the A/T system with N1 Limit values,
  • A/T is using a degraded N1 thrust limit from the related EEC
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2
Q

EGT Start Limit Redlines

A
  • Shown for ground starts and some in-flight starts as determined by EEC,
  • Displayed until the engine achieves Stabilized IDLE (approximately 59% N2)
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3
Q

EEC Abnormal Start Protections

A
  • For ground starts only it has 4 Protections:
    1-) Hot Start (rapid rise in EGT or approaching start limit),
    2-) Compressor Stall,
    3-) EGT Start Limit Exceedences,
    4-) Wet Starts (15s)
  • For all EEC turns off ingnition and shuts off fuel to the engine,
  • For Hot start and Compressor Stall, EGT white box flashes white,
  • If EGT limit exceeded both box and dial turns initially. Turns to white when below limit,
  • After engine shutdown it turns to red again
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4
Q

ENG FAIL Alert

A

Displayed:
- In amber and on the EGT indicator,
- Engine operating below sustainable IDLE (< 50% N2) and,
- Engine Start Lever in IDLE position

Alert remains until:
- Engine recovers or,
- Engine Start Lever moved to CUTOFF or,
- Engine Fire Switch pulled

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5
Q

Upper DU Engine Alerts

A
  • Illuminates amber,
  • All boxes blink for 10s,
  • After 10s related alert remains on steady
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6
Q

Engine Alerts Blinking Inhibit

A
  • During T/O from 80KT to 400FT or 30s after reaching 80KT, whichever occurs first,
  • During landing below 200FT until 30s after touchdown,
  • When blinking inhibited, alerts illuminate steady
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7
Q

Secondary Engine Indications Automatic Pop-up

A
  • Inflight when an Engine Start Lever moved to CUTOFF,
  • Inflight when an engine fails,
  • When a secondary engine parameter exceeds normal operating range,
  • Once displayed they cannot be cleared until the condition is no longer present
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8
Q

Low OIL PRESS Amber Band

A
  • Not displayed below 65% N2,
  • Variable depending on N2 above 65%
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9
Q

OIL QTY Windmilling Value

A

As low as zero is normal if windmilling N2 RPM < 8%

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10
Q

X-BLD

A
  • Location is above N2 dial,
  • Displayed when airspeed is less than required for windmilling start
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11
Q

ENGINE START Switch GRD

A
  • Opens Start Valve (using Battery power),
  • Closes Engine Bleed Valve (using Battery power),
  • For ground starts, arms selected igniter to provide ignition when Engine Start Lever is moved to IDLE,
  • For inflight starts, arms both igniters to provide ignition when Engine Start Lever is moved to IDLE,
  • Releases to OFF at Start Valve Cutout
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12
Q

ENGINE START Switch OFF

A

Ignition is normally OFF but both igniters activated when Engine Start Lever is in IDLE and:
- An uncommanded rapid decrease in N2 occurs or,
- N2 is between 57% and 50% or,
- Inflight, N2 is between idle and 5%

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13
Q

ENGINE START Switch CONT and FLT

A

CONT:
- Provides ignition to selected igniters when engine is operating and Engine Start Lever is in IDLE,
- Inflight, provides ignition to both igniters when N2 is below idle and Engine Start Lever is in IDLE

FLT:
- Provides ignition to both igniters when Engine Start Lever is in IDLE

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14
Q

REVERSER Light

A

Illuminates when:
- Isolation Valve or Thrust Reverser Vontrol Valve is not in commanded position,
- One or more Thrust Reverser sleeves are not in commanded state,
- Auto-restow circuit has been activated,
- A failure has been detected in Synchronizaiton Shaft Lock circuitry

During normal operation:
- Thrust Reverser commanded to stow and extinguishes 10s later when Isolation Valve closes,
- If illuminated more than 12s, MASTER CAUTION and ENG illuminates,

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15
Q

ENGINE CONTROL Lights

A

Illuminates for a Non-dispatchable fault and operates when:
- Engine is operating and,
- Airplane on ground and,
- Below 80KT prior to T/O or,
- Approximately 30s after touchdown

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16
Q

EEC Switches

A

ON:
- If only ON shown, indicates normal control mode is selected,
- When ON is not in view, the EEC has been MANUALLY selected to the Hard Alternate mode

ALTN:
- EEC has AUTOMATICALLY or MANUALLY switched to alternate control mode,
- If both ON and ALTN in view, EEC has automatically switched to alternate mode,
- EEC provides rated thrust or higher

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17
Q

Reverse Thrust Lever Lock

A

Blocked at Reverse Idle position until related Thrust Reverser is > 60% deployed

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18
Q

Engine Start Levers IDLE

A
  • Energizes Ignition system through EEC,
  • Electrically opens Spar Fuel Shutoff Valve in the wing leading edge outboard of the pylon,
  • Electrically opens Engine-Mounted Fuel Shutoff Valve via the EEC
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19
Q

APU OVERSPEED Light

A

Illuminated when:
- APU RPM limit has been exceeded resulting in an automatic shutdown,
- Overspeed Shutdown Protection feature has failed a self-test during a normal APU shutdown,
- If illuminated when APU switch is placed to OFF, light extinguishes after 5 minutes,
- Light is disarmed when APU switch is OFF

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20
Q

APU FAULT Light

A

Illuminated when:
- A malfunction exists causing APU to initiate an automatic shutdown,
- If illuminated when APU switch is placed to OFF, light extinguishes after 5 minutes,
- Light is disarmed when APU switch is OFF

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21
Q

APU LOW OIL PRESSURE Light

A

Illuminated when:
- During start until APU oil pressure is normal,
- Oil pressure is low causing an automatic shutdown (after start cycle complete),
- If illuminated when APU switch is placed to OFF, light extinguishes after 5 minutes,
- Light is disarmed when APU switch is OFF

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22
Q

Engines General

A
  • CFM56-7 axial flow,
  • Dual rotor N1 and N2,
  • N1 consists of: Fan, LP Compressor and LP Turbine,
  • N2 consists of: HP Compressor and HP Turbine,
  • N2 rotor drives Engine Gearboxes,
  • Bleed air powered Starter Motor is connected to N2 rotor
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23
Q

EEC

A
  • Electronic Engine Control,
  • Dual channel EEC regulates each engine,
  • With each engine start or attempt, the EEC alternates between control channels,
  • Monitors A/T and Flight Crew inputs to automatically set engine thrust,
24
Q

EEC and Engine Indications

A
  • When EEC not powered N1, N2, Oil Quantity and Engine Vibration are displayed directly from engine sensors,
  • During Battery Start only N1, N2 and Oil Quantity is shown,
  • Positioning ENGINE START switch to GRD supplies power to the EEC and displays all engine parameters,
  • EEC is not powered until 15% N2
25
Q

EEC Modes

A

Normal:
- Uses sensed flight conditions and bleed air demand to calculate N1 thrust ratings,
- EEC compares commanded N1 and actual N1 adn adjusts fuel flow to achieve the commanded N1

Soft Alternate:
- If required signals are not available to operate in the normal mode, EEC automatically changes to Soft Alternate mode,
- Loss of either DEU results in Soft Alternate Mode,
- The ALTN and ON lights shown together,
- EEC uses the last valid flight conditions to define engine parameters,
- If ambient conditions change, thrust rating shortfalls or exceedances may occur

Hard Alternate:
- Soft Alternate changes to Hard Alternate by: retarding the thrust levers to IDLE (ON light remains) or,
- Manually selecting ALTN with the EEC switch (ON light extinguishes),
- Thrust is always equal or greater than normal mode for the same thrust lever position,
- EEC limiting is not provided and Maximum Rated Thrust may be reached before the forward stop

26
Q

Full Rated T/O and Maximum Rated Thrust

A

In normal mode:
- Full Rated T/O Thrust is available before the forward stop,
- The Maximum Rated Thrust is available at the forward stop

27
Q

EEC Structural Limit Protection

A
  • EEC provides N1 and N2 redline overspeed protection in both normal and alternate modes,
  • EEC does not provide EGT redline exceedance protection
28
Q

Approach Idle Operation

A

General:
- N1 and N2 RPM is higher than Flight Idle,
- This improves engine acceleration time in the event of a go-around,

Engages when:
- EAI Switch ON for either engine or,
- < 19000FT MSL and left or right Main Landing Gear is down and locked,
- < 19000FT MSL and left or right Flaps are 15 or greater,
- If there is a fault preventing EEC to receive Flaps or Gear Signals, engages < 19000FT,
- Maintained until after touchdown when Ground Idle is selected

29
Q

Engine Fuel System

A
  • Fuel delivered under pressure from fuel pumps,
  • Flows through Spar Fuel Shutoff Valve at the engine mounting wing station,
  • Then passes through 1st stage Engine Fuel Pump where pressure increased,
  • Then passes through 2 fuel/oil Heat Exchangers (IDG and Main Engine Oil),
  • After that a Fuel Filter removes contaminants (bypasses it if it becomes saturated),
  • Then 2nd stage Engine Fuel Pump adds more pressure before fuel reaches HMU,
  • EEC meters fuel through HMU, After HMU fuel flows through Engine Fuel Shutoff Valve
30
Q

Fuel Flow Measurement Location

A

After passing Engine Fuel Shutoff Valve

31
Q

Engine Oil System

A
  • System pressurized by the Engine Driven Oil Pump,
  • From the pump it goes to engine bearings and gearbox,
  • Sensors for oil temperature and pressure indicators and LOW OIL PRESSURE alert are downstream of pump prior the engine lubrication,
  • Oil is returned to the tank by Engine Driven Scavenge Pumps,
  • After the pump oil passes through Scavenge Filter (bypasses it if it becomes saturated),
  • 2 Pressure sensors before and after Scavenge Pump used to illuminate OIL FILTER BYPASS
  • Prior returning to the tank, the Oil passes through the Main Engine Oil Cooler
32
Q

Fuel Flow and EGT During Engine Start

A
  • Initial Fuel Flow indications lag actual Fuel Flow by approximately 2s,
  • During engine start an EGT rise may occur before Fuel Flow indication
33
Q

Engine Ignition System Power Source

A
  • Left Igniter receives from the associated AC Transfer Bus,
  • Right Igniter receives from AC Standby Bus
34
Q

Auto-Relight

A
  • Provided for Flameout Protection,
  • Whenever EEC detects an Engine Flameout, both igniters are activated,
  • Flameout detected when: Uncommanded rapid decrease in N2 occurs or N2 is below idle RPM
35
Q

Inflight Starting EGT Limit

A
  • Can be shown depending on the start logic as determined by the EEC,
  • If only the EGT limit is shown, this is the inflight start EGT limit,
  • If both EGT Redline and EGT Start Limit are shown, EGT Start Limit is the start limit
36
Q

Thrust Reverser Basic Operation

A
  • Aft movement of the L & R translating sleeves causes Blocker Doors to deflect Fan Discharge Air forward,
  • Air deflected through Fixed Cascade Vanes, producing reverse thrust
37
Q

Thrust Reverser Deployment

A
  • Can be deployed when RA senses less than 10FT or Air/Ground Safety Sensor in the ground mode,
  • When selected:
    1-) Electro-mechanical Lock releases,
    2-) Isolation Valve opens,
    3-) Thrust Reverser Control Valve moves to deploy position, allowing hydraulic pressure to unlock and deploy the Reverser System,
    4-) An Interlock mechanism initially restricts movement of the Reverse Thrust Lever movement (Sleeves > 60% open),
    5-) After Sleeves are deployed, Reverse Thrust Lever can be raised to Detent 2 or further to Maximum
38
Q

REV Indication

A

Amber:
- When either Reverser Sleeve moves from the stowed position,

Green:
- Thrust Reverser reaches deployed position

39
Q

Thrust Reverser Stowing

A
  • Downward motion of Reverse Thrust Lever past Detent No. 1 (Reverse Idle) initiates the stow command,
  • When Reverse Thrust Lever reaches full down position, Control Valve moves to the stow position,
  • Allowing hydraulic pressure to stow and lock the Reverser Sleeves,
  • After the Thrust Reverser stowed, the Isolation Valve closes,
  • Then Electro-mechanical Lock engages
40
Q

Thrust Reverser Stowing Caution

A
  • A pause in movement of the Reverse Thrust Lever past Detent No. 1 toward the stow position,
  • May cause MASTER CAUTION and ENG lights to illuminate,
  • A pause of approximately 16s engages Electro-mechanical Lock and prevents Sleeves from further movement,
  • Cycling the Thrust Reversers may clear the fault
41
Q

Thrust Reverser Stowed Protections

A
  • In stowed position an Electro-mechanical Lock and,
  • Hydraulically operated Locking Actuator inhibit motion to each Reverser Sleeve until extension is selected,
  • Also has an Auto-Restow circuit
42
Q

Thrust Reverser Auto-Restow Circuit

A
  • Compares actual and commanded position,
  • In the event of incomplete stowage or uncommanded movement circuit opens the Isolation Valve,
  • Commands the Control Valve to the stow position directing hydraulic pressure to stow the sleeves,
  • Once activated, the Isolation Valve remains open and Control Valve held in stowed position until,
  • Thrust Reverser is commanded to deploy or corrective maintenance action is taken
43
Q

Airborne Vibration Monitoring System

A
  • Primary function is the display of Low and High Pressure Rotor Synchronous vibration,
  • Also used to balance the Low Pressure Rotor,
  • Balancing reduces high vibration or audible noise and tactile vibration
44
Q

APU

A
  • Auxiliary Power Unit is a self-contained gas turbine engine installed within a fireproof compartment
45
Q

APU Fuel Supply

A
  • Comes from left side of the fuel manifold when AC Fuel Pumps are operating,
  • If AC Fuel Pumps not operating, fuel is suction fed from No. 1 tank,
  • During APU operation, fuel is automatically heated
46
Q

APU Engine and Cooling Air

A
  • Engine air enters via inlet door on the right side of the fuselage,
  • APU exhaust gases discharge via Exhaust Muffler on the tail,
  • APU cooling air enters via Cooling Air Inlet above the Exhaust Outlet,
  • Cooling air circulates through the APU compartment, oil cooler and vents via Exhaust Outlet
47
Q

Electrical Requirement For APU Operation

A
  • Battery Switch must be ON,
  • Power to start comes from AC Transfer Bus 1 or the Main Battery if AC power not available,
  • Moving Battery Switch to OFF automatically shuts down APU due to power loss to the Electronic Control Unit
48
Q

APU Start

A
  • Moving APU switch to START initiates opening of the Air Inlet Door,
  • When Inlet Door reaches fully open position, the start sequence begins,
  • After reaching proper speed, ignition and fuel are provided,
  • When APU is ready to accept a bleed air or electrical load the APU GEN OFF BUS light illuminates
49
Q

APU Indications During Start

A
  • EGT may fluctuate between 0-1100 degrees,
  • LOW OIL PRESSURE light may cycle on and off several times
50
Q

APU Start With Battery Only

A

When the AC Meters Selector is set to APU GEN:
- CPS FREQ indication will be blank,
- AC VOLTS indication will be 0,
- When APU GEN OFF BUS light illuminates actual values will be shown

51
Q

Start Cycle Duration

A

May take as long as 120s

52
Q

Recommended Wait Time for APU Bleed Air

A
  • After start, operate the APU for 2 full minutes before using it as a bleed air source,
  • Before shutdown, operate APU for 1 full minute with no bleed air,
  • When the APU switch moved to OFF, this time delay is met automatically
53
Q

APU Shutdown

A
  • Shutdown occurs automatically 60s after APU switch moved to OFF,
  • When the APU speed decreases sufficiently during shutdown, the Fuel Valve amd Inlet Door close,
  • If the Fuel Valve does not close, the FAULT light illuminates after approximately 30s,
  • Immediate shutdown can be done by pulling APU Fire Switch
54
Q

ECU

A
  • Electronic Control Unit of the APU,
  • If detects a fault that may cause damage to the APU or the aircraft,
  • It will automatically execute a protective shutdown,
  • Automatically controls APU speed through the Electronic Fuel Control
55
Q

APU Bleed and Electrical Load Shedding

A

If EGT raises above acceptable levels:
- During engine start, electrical load shedding occurs first,
- Other times, Inlet Guide Vanes move toward a closed position, reducing bleed air extraction first

56
Q

APU Automatic Load Shedding

A

If the APU is the only source inflight:
- All Galley and Main Busses are automatically shed,
- If still not enough both IFE Busses are automatically shed

On the ground:
- APU attempts to carry a full electrical load,
- If overload sensed, APU sheds Galley and Main Busses until the load is within limits

Manual restoration of Galley and Main Bus power can be attempted via cycling CAB/UTIL switch

FCOM System Description (10 decks)

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