APU

Question 0

What should be visually observed on the of the A/C before turning on the APU?

Answer 0

1. Grounding strap
2. Bomb bay door (pins)
3. Flap position
4. Chains loosened
5. Landing gear pins
6. Butt plug
7. Covers off PITOT AOA
8. O2 overboard discharge disk (green)
9. Exhaust door is free of cracks & missing rivets

Question 1

Who should be on board the A/C during APU operation?

Answer 1

An APU qualified operator.

Question 2

APU HRD bottle

Answer 2

High Rate Discharge

500+ PSI

Question 3

Refrigeration Turbine Hyd Fluid

Answer 3

3/4 +

Question 4

What position does the APU & fire extinguisher safety switch have to be in?

Answer 4

Normal and the panel door closed.

*safety switch prevents the APU from turning on, it locks the intake and exhaust doors and prevents the extinguishers from going off.

Question 5

APU oil reservoir

Answer 5

More than 1/2 in the bottom gauge.

Question 6

Air multiplier oil reservoir

Answer 6

More than 1/2

Question 7

What should be checked on the air multiplier blades?

Answer 7

Check blades for

• scored
• scratched
• corroded

Question 8

What position should the sonobuoy disable door be in?

Answer 8

Opened

Question 9

Interior checks not including circuits and flight station.

Answer 9

1. Check main load center personnel and gear adrift
2. Ensure bus feeders and pushed in (3)
3. Probe heaters (off)

Question 10

Circuit breaker checks

Answer 10

1. HSI (C rack)
2. FDI (lower FLC)
3. INS (B rack)

Question 11

What is the minimum battery voltage?

Answer 11

22 VDC

Question 12

Flight station circuit breakers

Answer 12

All set except intake door breaker. (FLC)

Question 13

Red guarded switches

Answer 13

Closed

Question 14

Flight station switches position

Answer 14

OFF, SAFE, NORMAL

Question 15

Land gear handle

Answer 15

Down

Question 16

Wing flap lever

Answer 16

Agrees with flap position

Question 17

Bombay door switch

Answer 17

Agrees with bomb bay position

Question 18

Emergency shut down handles

Answer 18

Pushed in

Question 19

Checking the fire detector

Answer 19

Hold in horn override while flipping the detector switch until beep is heard and panels lights illuminate. Repeat once more.

Question 20

APU arming switch

Answer 20

Red guarded with shear wire.

Question 21

Starting the APU

Answer 21

1. Control switch on
2. Wait for exhaust door to open
3. Set intake door breaker
4. Control switch to start (release immediately)
5. Generator switch on

Question 22

Fuel quantity

Answer 22

Tank 2 & 3 - at least 1,000lbs

Question 23

3 reasons the APU turns off

Answer 23

1. Loss of oil pressure
2. Fire in the APU compartment 400 degrees
3. Over speed 106%

Question 24

APU limits for the -10

Answer 24

Exhaust temp: max 732 Celsius
EGT 10 sec max: 710 Celsius
EGT max continuous: 649 Celsius

RPM: 98-102%
Over speed: 106%

Question 25

Ground air conditioning

Answer 25

1. Set controllers to manual.
2. Actuate ground AC switch
3. Observe spread on Engine Driven Compressor I/D needles
4. Start at 2 dot or higher.

Question 26

Max temperature

Answer 26

Duct temp: >5 <=27 Celsius

Question 27

Dehumidification

Answer 27

15 mins of dehumidification when APU is operated for at least 30 mins. Set controllers to auto 2 dot and slowly to 3 dot.