"APU Practice test"

Question 1

Describe the start/on-speed sequence. (indication, time limits, etc)

Answer 1

• START light (4) goes out at 35 percent RPM.
• ON SPEED light (3) comes on within 35 seconds after START light comes on.
• ON SPEED light (3) comes on at 95 percent RPM and stays on.
• Tachometer (1) indicates 100 ( 2) percent RPM.
• EGT indicator (2) does not exceed 620oC.

Question 2

What is the normal rpm operating limits?

Answer 2

TACH 100+-2% RPM

Question 3

At what RPM does the APU overspeed?

Answer 3

110% RPM

Question 4

What are the limitations of the APU generator?

Answer 4

115+-3V & 400+-20Hz

Question 5

What is the bleed down limitations?

Answer 5

83-0486< 8.5 seconds. 30 to 15.

83-0486 and > 16 seconds.

Question 6

What switches need to be actuated to accomplish the bleed down?

Answer 6

APU BA Valve BA SW to open/on. wait till is gets up to at least 35PSI and put sw to CLOSED/OFF.

Question 7

What are the EGT limitations?

Answer 7

620 degrees celcius

Question 8

What should you do before applying bleed air to the manifold?

Answer 8

Make sure the props are clear.

Question 9

What tank supplies fuel to the APU?

Answer 9

2

Question 10

What is the required fuel capacity? If it is below the required capacity, can the APU still be started? If so, what mustbe done?

Answer 10

2 - 2,000 lbs. if below 2,000 lbs turn boost pump on.

Question 11

What is the capacity of the oil tank?

Answer 11

4 quarts

Question 12

What is the capacity of the oil tank and system?

Answer 12

6 quarts

Question 13

How often should you check the fuel SOV? What indicates a bad SOV?

Answer 13

first APU start of the day. Its bad if fuel steadly flows after the ops chk.

Question 14

What is the primary purpose of the APU?

Answer 14

supplies BA for starting engines, operation of other BA systems & mechanically drives an AC GEN.

Question 15

At what PSI does the APU door close?

Answer 15

20PSI

Question 16

Can you operate the APU with a failed inlet door?

Answer 16

Yes. You need to reposition the door actuator (if running apu on ground). It is not recommended in flight.

Question 17

What AC bus does the APU GEN power?

Answer 17

…

Question 18

When starting the APU using battery power, what battery voltage is required?

Answer 18

21V

Question 19

When starting the APU using battery power, when should you turn on the APU GEN?

Answer 19

…

Question 20

Where is the oil tank located (approximate)?

Answer 20

…

Question 21

what is the starter duty cycle?

Answer 21

1 minute on and 4 minutes off

Question 22

Assuming the APU hasn’t reached 35% RPM, what is the time limit before you must stop the APU?

Answer 22

1 minute

Question 23

Can the A/C fly without the APU power?

Answer 23

YES.

Question 24

When using external electrical power, is it required to turn the APU GEN on?

Answer 24

NO. once in flight if the APU is turned on it becomed the emergency generatore and will take over the essential bus.

Question 25

If you put the APU to stop and it doesn’t stop, what should you do?

Answer 25

…

Question 26

Can you radio tower from the FE position?

Answer 26

YES. (275.8 UHF)

Question 27

What is the Ground frequency for LRAFB?

Answer 27

275.8 UHF

Question 28

What bus powers the APU?

Answer 28

isolated DC bus

Question 29

What percent does the APU door open to on the ground?

Answer 29

35 degrees

Question 30

What percent does the APU door open in flight?

Answer 30

15 degrees

Question 31

What is LRAFB ground frequecy? UHF or VHF?

Answer 31

UHF 275.8

Question 32

Placing the APU cntrl switch to stop is a functional check of what protections component?

Answer 32

…

Question 33

What is the purpose of tying the DC bus for APU operations?

Answer 33

…

Question 34

What does the acronymn stand for?

Answer 34

…

Question 35

How do you shutdown the APU if placing the APU control SW to stop does not work?

Answer 35

…

Question 36

What are the real names for the APU components commonly called “salt and pepper shakers”

Answer 36

ignition circuit relay