APU

Question 1

The APU EGT indicator remains powered for ____ minutes after shutdown to provide display of residual EPU EGT.

Answer 1

5 min

Question 2

APU: amber OVERSPEED light?

Answer 2

APU RPM has been exceeded and APU has shut down automatically.

Question 3

APU: amber FAULT light?

Answer 3

auto shut down due to malfunction.

Question 4

APU: amber LOW OIL PRESSURE light?

Answer 4

normal during APU start. If on after start, APU will shut down automatically.

Question 5

Blue APU MAINT light?

Answer 5

mx issue with APU but can still be operated.

Question 6

APU ECU provides protection for what?

Answer 6

Overspeed
Low oil pressure
High oil temp
APU fire
fuel control unit failure
EGT exceedance
Other system faults

Question 7

T/F: Depending on ambient conditions, the ECU will auto shed bleed air and/or electrical loads to maintain APU speed and EGT margins.

Answer 7

true

Question 8

During engine start, which gets shed first, elec or bleed air?

Answer 8

elec first then bleed air.

Question 9

Other than engine start, which gets shed first, elec or bleed air?

Answer 9

bleed air then elec

Question 10

In flight if APU is only source of elec power, which buses are auto shed?

Answer 10

GALLEY and MAIN BUSSES. Both IFE busses will shed if elec load is still too high.

Question 11

T/F: On the ground, the APU will always attempt to carry a full load.

Answer 11

true

Question 12

The APU will normally draw fuel from the _____side of the fuel manifold provided AC fuel pumps are operating.

Answer 12

Left side

Question 13

If fuel pumps not operating, the APU will ______feed.

Answer 13

suction.

Question 14

What is the routing for the APU cooling air?

Answer 14

circulates through the APU compartment, passes through oil cooler and then discharges.

Question 15

The APU won’t operate unless:

Answer 15

1. APU fire handle is in
2. APU gnd control panel in
3. APU fire switch on overheat/fire panel-in
4. BAT switch -on

Question 16

Normal APU starts get AC power from which bus?

Answer 16

AC TRANSFER BUS 1

Question 17

Blue APU GEN OFF BUS means what?

Answer 17

APU is ready to accept a bleed or electric load. Also shows when APU start cycle is completed.

Question 18

The APU start cycle can take as long as _______.

Answer 18

120 seconds

Question 19

Operate the APU for _______ prior to selecting a bleed source

Answer 19

1 full minute

Question 20

T/F: Run the APU for 1 full minute without a bleed air source before shutting down.

Answer 20

true

Question 21

T/F: The APU auto shuts down 60 seconds after positioning the switch to OFF.

Answer 21

true