APU Flashcards
What causes an automatic EMER. SHUTDOWN of the APU? When is this facility available?
- APU fire on the ground.
- Pressing the APU fire on the exterior panel.
Why would the APU continue to run after being selected OFF?
If using APU bleed air, the APU keeps running for cooling period of 60sec.
What happens if excessive EGT is sensed?
FAULT amber light, and a caution appears on ECAM. Followed by an automatic shutdown.
AUTO SHUTDOWN is available during which phases of flight? And EMER SHUTDOWN (Fire)
1500’ – 800’
What causes the FLAP to OPEN? What does the message FLAP OPEN mean exactly?
- When MASTER SW p/b is pressed.
- In green when APU air intake flap is fully open.
- In amber after 3min APU has been switched OFF.
What happens if the START button is pressed immediately after the MASTER button is pressed?
- Green light comes on when N is >99.5% or 2sec after N reaches 95%
- APU can now be used for electrics and/or bleed
What is the Maximum altitude for APU start?
- 41,000’ by electrical power
- 25,000’ by battery only
- 14,500’ on the ground
What are the altitude limitations for the use of APU bleed & packs?
2 packs: 15,000’
1 pack: 22,500’
What would you do if the SD showed LO OIL LVL?
- Refill the oil
- Low APU oil when the aircraft is on the ground, and the APU is not running.
- The APU may be started ad operated even if the LOW OIL LEVEL ECAM advisory is displayed.
- Maintenance action is required within next 10hrs of APU operation.
What is the APU start limitation?
After 3 starter motor duty cycles, wait 60min before attempting 3 more cycles.
One.
How many generators has the APU?
The APU AVAIL appears in green when APU N is above 95%.
When does the APU AVAIL appear green?
The basic element of the APU is a single-shaft gas turbine that delivers mechanical shaft power for driving the accessory gearbox (electrical generator starter etc.) and produces bleed air (engine starting and pneumatic supply).
What is the basic element of the APU?
The APU will run for a cooling period because you have been using the APU bleed.
You switched the APU off. Why do you still have the APU AVAIL indications?
The APU can be started at any altitude using normal aircraft electrical power.
The APU may be started up to which altitude?
The ECB is a full-authority digital electronic controller that performs the bulk of the APU system logic for all modes of engine operation such as: Sequences the start and monitor it monitors speed and temperature monitors bleed air sequences the shutdown and controls the automatic shutdown.
What is the purpose of the Electronic Control Box (ECB)?
APU fire warnings operate in the cockpit and in the nose gear bay the AVAIL light goes out the FAULT light comes on the APU shuts down and the APU fire extinguisher discharges.
What occurs in case of an APU fire with no crew in the cockpit?
In flight the APU backs up the electrical system and the air conditioning and it can be used to start the engines.
What is the purpose of the APU in flight?
The left fuel feed line supplies the APU. The required pressure is normally available from the tank pumps. If pressure is not available (batteries only or pumps off) the APU FUEL PUMP starts automatically. The ECB controls the fuel flow.
How does the APU fuel system work?
When selected to OFF the APU generator field is de-energized.
What is the function of the APU GEN pushbutton located on the overhead electrical panel?
The left fuel feed line supplies the APU normally via the tank pumps. The APU FUEL PUMP starts automatically if pressure is not available (batteries only or pumps off).
How does the fuel supply work for the APU?
20,000 Feet
What is the highest altitude the APU can supply bleed air for engine start while providing electrical power?
Electric
Does APU air or electric have priority?
The APU is available to provide electrical power and/or bleed air
What does the green “AVAIL” light on the APU start pushbutton indicate?
