APU

Question 1

Where is the APU situated

Answer 1

The Auxiliary Power​ Unit (APU) is​ self-contained. It is located​ in a​ fire-proof enclosure at​ ​the ​ rear ​ fuselage ​ aft ​ of​ ​ the ​ rear ​ pressure ​ bulkhead

Question 2

What tank does the fuel normally come from

Answer 2

LH collector tank

Question 3

What electrical power is used for the operation

Answer 3

DC electrical power

Question 4

What can the APU supply

Answer 4

APU supplies Electrical power and bleed air on ground

Inflight APU supplies Electrical power only

Question 5

How do you start the APU

Answer 5

Pull and rotate APU selector to start then release to ON

Question 6

What does the AVAIL light tell you

Answer 6

After ​ the ​ APU ​ reaches operating ​ speed ​ the​ ​AVAIL light comes on and electrical power is available. After approximately 2 minutes ​at operating speed bleed​ air will be available.​

Question 7

When is bleed air available after start

Answer 7

After 2 mins

Question 8

What faults will shut down the APU in flight and what indications do you get

Answer 8

Start time > 90 secs, overspeed, fire

Question 9

What faults will shutdown the APU on the ground and what indications do you get

Answer 9

In case of APU fire (see FIRE PROTECTION) or APU over​ speed, the APU shuts down​ ​automatically. The APU cannot be restarted after an over speed fault. On the ground the​ ​APU will also shut down automatically in case of​ a failure. Failures that might occur are​ ​low oil pressure, high oil temperature, ​ high exhaust gas temperature, and other internal ​APU ​ failures. ​ A ​ continuous ​ self-test ​ feature ​ allows ​ unattended ​ APU ​ operation ​ on ​ the​ ​ground

Question 10

What happens if the APU load becomes excessive

Answer 10

It decreases the bleed air

Question 11

May the APU operate unattended on the ground? Why

Answer 11

Yes it can but You need Flight crew or engineers in the vicinity of the aircraft.

Question 12

What can you do the enhance cabin cooling after landing in hot climates

Answer 12

When​ operating​ in hot climates it is recommended to start the​ APU shortly​ before​ landing​ in ​order​ to have APU bleed air available for​ cabin​ cooling​ after​ landing.​ APU bleed air ​is​ available​​ ​2 minutes​ after​ APU start

Question 13

When is it recomended that you leave the APU running for a flight

Answer 13

When 1 Gen has failed, when checklist or MEL tells you to do so.

Question 14

Why shouldn’t you operate the APU without the BAT switch on or without external power connected and accepted

Answer 14

DO​ NOT​ OPERATE THE​ APU WITH​ THE​ BATTERIES​ SWITCH​ OFF​ ​AND​ ​ WITH​ ​ NO​ ​ EXTERNAL​ ​ POWER ​ CONNECTED ​ AS​ ​ AUTOMATIC​ ​EXTINGUISHING WILL​ NOT​ TAKE​ PLACE IN CASE OF​ AN APU FIRE

Question 15

Where and when is the APU page displayed

Answer 15

When you start APU, exceeds limitations or press the button