Systems - APU and Powerplant Flashcards by Vincent Bertucci

What does turning the APU Master knob to the ON position do?

Energizes the Electronic Sequence Unit (ESU) (or FADEC)
Commands the fuel shutoff valve to open
Enables indication and alarms on the EICAS-
Allows the APU to keep running after starting

How well did you know this?

Not at all

Perfectly

Where is the APU located?

Tailcone of the aircraft, aft of a firewall

How well did you know this?

Not at all

Perfectly

What are the different electrical sources used to start the APU?

Battery 2
Battery 2 assisted by engine driven generator(s)
Ground Power Unit

How well did you know this?

Not at all

Perfectly

After starting, when is electrical power available from the APU?

7 seconds after reaching 95% rotor speed

How well did you know this?

Not at all

Perfectly

When does the APU starter-generator disengage during the start cycle?

When rotor speed exceeds 50%, the FADEC de-energizes the starter (at 70% rotor speed the FADEC de-energizes the ignition exciter).

How well did you know this?

Not at all

Perfectly

How does the APU receive its fuel?

Tank #2

(Can receive fuel from Tank #1 if Crossfeed is selected to LOW2 and electric fuel pump for Wing Tank #1 is on..

How well did you know this?

Not at all

Perfectly

What controls the start and normal operation of the APU?

The Electronic Sequence Unit (ESU)

the APU’s own FADEC

How well did you know this?

Not at all

Perfectly

Which electrical busses can the APU energize as the sole source of electrical power?

In flight: all main busses except Shed busses

On ground: all busses provided the Shed Bus switch is in OVRD position

How well did you know this?

Not at all

Perfectly

What is the max altitude for an APU start?

FL300

How well did you know this?

Not at all

Perfectly

What is the max altitude for APU operation?

FL370

How well did you know this?

Not at all

Perfectly

What are the required cool-down periods for APU start?

Between three consecutive attempts: 1 min off

Between two series of three consecutive attempts 30 mins off

How well did you know this?

Not at all

Perfectly

How is a fire detected in the APU?

By it’s own dedicated fire loop

How well did you know this?

Not at all

Perfectly

How is a fire extinguished in the APU?

By it’s own dedicated extinguishing bottle.

How well did you know this?

Not at all

Perfectly

What does the APU Fire Extinguishing Button do?

Closes APU fuel shutoff valve

- Discharges APU fire bottle

How well did you know this?

Not at all

Perfectly

Under what conditions will the APU automatic shutdown occur (on the ground / in flight)?

On ground: any fire, fault or failure
In flight any fault or failure
[for full list see ASM 37-9.1]

How well did you know this?

Not at all

Perfectly

What is the max electrical load allowed on the APU generator?

Up to FL300: 400A

Above FL300: 300A

How well did you know this?

Not at all

Perfectly

What is the minimum battery temperature and voltage for APU start?

Min temp: -20ºC
Min battery voltage: 23.5 (battery or GPU start ok)
- 19V to 23.5V: GPU required for start
- below 19V: battery must be removed (recharged by maintenance)

How well did you know this?

Not at all

Perfectly

What type of engines are on the aircraft?

Rolls Royce AE3007A1E

How well did you know this?

Not at all

Perfectly

What are the 3 pilot selectable thrust modes for takeoff?

ALT T/O-1: normal - best durability and economy
T/O: medium thrust level
E T/O: highest level

How well did you know this?

Not at all

Perfectly

Which two compressor stages are bleed air tapped from?

9th and 14th stages

How well did you know this?

Not at all

Perfectly

When does the high-stage valve automatically open to allow 14th stage bleed air to supply the system?

low thrust settings
cross-bleed starts
pneumatic anti-ice activated

How well did you know this?

Not at all

Perfectly

How is the accessory gearbox powered?

Via a tower shaft connected to the high pressure turbine (N2)

Which components are located on the accessory gear box?

HOPFAG
Hydraulic Pumps
Oil Pumps
Permanent Magnetic Alternators
Fuel Pumps
Air Turbine Starter
Generators (DC)

What are the three sources of air for engine start?

APU bleed air
Cross bleed air (requires 83% N2 on operating eng)
External air

What is the preferred source of air for engine start?

APU bleed air

What is the FPMU and what does it do?

- Controls and supplies fuel to engine nozzles | - Controls the compressor variable geometry vanes

What controls operation of the FPMU?

FADEC

How does the fuel shutoff valve work?

Located in the wing box in the belly of the aircraft, can only be activated by pulling the engine fire extinguishing T-handle.

What are the two ways pilots can shut off fuel to the engines?

Start/Stop Selector: cuts off fuel at the engine Fire Extinguishing Handle: closes fuel shutoff valve at fuel source in wing box. (If only T-handle is pulled, engine may continue to operate for up to 1 minute.)

Which MFD page displays engine oil quantity and pressure?

Oil qty: MFD T/O page Oil Press: EICAS

What is the minimum oil level for dispatch?

8 quarts

When does the engine oil quantity indication text turn amber?

Below 6 quarts

What is the primary source for engine control?

FADEC

What provides the engine ignition source?

Permanent Magnetic Alternators (PMAs) | On engine AGB driven by N2 via tower shaft.

At what N2 rotor speed will the igniters energize on start?

At around 10% N2, there is enough rotation to drive the tower shaft and PMAs to power the igniters.

When do the FADECs begin to receive power on start?

At 50% N2, PMAs will begin to power the FADECs.

How is the FADEC powered below 50% N2?

Essential busses

How do the PMAs work?

Self-contained magnets - convert mechanical energy into electrical energy. Generates an ignition source for engines then powers the FADECs.

How many igniters are in each engine?

2 igniters per engine

What does the Engine Ignition Switch in the AUTO position do?

Allows the FADEC to control how many igniters are used for start: - on ground: 1 igniter for normal start - auto-relight: 2 igniters (ground or in flight)

What does the Ignition switch in the cockpit control?

OFF: no igniters fire / engine fuel valve remains closed if the engine is not running (used for dry-motoring); valve remains open if engine is at least in IDLE. ON: ignition remains constant with both igniters firing.

What thrust is provided when the thrust lever is in the detent position?

Full thrust for a given thrust mode (commanded by FADEC).

Where is the FADEC in command displayed?

On the EICAS, either A or B.

What happens when there is an inadvertent thrust reverser deployment in flight?

The FADEC automatically brings the thrust in the respective engine to IDLE, regardless of thrust lever angle.

How is the max available thrust for each selected takeoff thrust rating calculated?

By the FADEC with input from the pilot via the MFD T/O page (thrust mode, temp, and anti-ice mode). If takeoff data is not selected, the FADEC reverts to E T/O.

What happens if the thrust lever is forward of the IDLE position and the Start/Stop selectors are placed in the stop position?

The respective engine will NOT shut down without the thrust lever in the IDLE position.

What is the purpose of the ATTCS?

When the engine fails, the system automatically increases thrust on the operating engine to increase single-engine performance.

When will the FADEC select T/O RSV mode? | T/O mode?

When ATTCS receives an eng out signal. ALT T/O-1 ---> T/O-1 T/O ---> T/O RSV E T/O ---> E T/O RSV

What indication would indicate takeoff data was not accepted by the FADEC?

ENG NO T/O DATA displayed on EICAS | In the event data is not entered, FADECs revert to E T/O thrust.

How are thrust reversers activated/actuated/locked?

- electrically activated - hydraulically actuated - mechanically and hydraulically locked

What are the engine abort start criteria?

- No light off 10 seconds after fuel flow - ITT approaches start limit (800°C) (hot start) - N2 decreases/remains steady for > 30 sec (hung start) - N2 indicates no rotation up to 10 sec after start - Any unusual noise or vibration - Engine instruments indicate abnormal conditions - Flames are visible - Oil pressure does not reach 34 psi when stable

APU start is always accomplished using what kind of power?

Electrical

What does the E1(2) OIL LOW PRESS EICAS warning indicate?

Oil pressure < 34 psi