APU Flashcards
What should be visually observed on the of the A/C before turning on the APU?
- Grounding strap
- Bomb bay door (pins)
- Flap position
- Chains loosened
- Landing gear pins
- Butt plug
- Covers off PITOT AOA
- O2 overboard discharge disk (green)
- Exhaust door is free of cracks & missing rivets
Who should be on board the A/C during APU operation?
An APU qualified operator.
APU HRD bottle
High Rate Discharge
500+ PSI
Refrigeration Turbine Hyd Fluid
3/4 +
What position does the APU & fire extinguisher safety switch have to be in?
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.
APU oil reservoir
More than 1/2 in the bottom gauge.
Air multiplier oil reservoir
More than 1/2
What should be checked on the air multiplier blades?
Check blades for
- scored
- scratched
- corroded
What position should the sonobuoy disable door be in?
Opened
Interior checks not including circuits and flight station.
- Check main load center personnel and gear adrift
- Ensure bus feeders and pushed in (3)
- Probe heaters (off)
Circuit breaker checks
- HSI (C rack)
- FDI (lower FLC)
- INS (B rack)
What is the minimum battery voltage?
22 VDC
Flight station circuit breakers
All set except intake door breaker. (FLC)
Red guarded switches
Closed
Flight station switches position
OFF, SAFE, NORMAL
Land gear handle
Down
Wing flap lever
Agrees with flap position
Bombay door switch
Agrees with bomb bay position
Emergency shut down handles
Pushed in
Checking the fire detector
Hold in horn override while flipping the detector switch until beep is heard and panels lights illuminate. Repeat once more.
APU arming switch
Red guarded with shear wire.
Starting the APU
- Control switch on
- Wait for exhaust door to open
- Set intake door breaker
- Control switch to start (release immediately)
- Generator switch on
Fuel quantity
Tank 2 & 3 - at least 1,000lbs
3 reasons the APU turns off
- Loss of oil pressure
- Fire in the APU compartment 400 degrees
- Over speed 106%
APU limits for the -10
Exhaust temp: max 732 Celsius
EGT 10 sec max: 710 Celsius
EGT max continuous: 649 Celsius
RPM: 98-102%
Over speed: 106%
Ground air conditioning
- Set controllers to manual.
- Actuate ground AC switch
- Observe spread on Engine Driven Compressor I/D needles
- Start at 2 dot or higher.
Max temperature
Duct temp: >5 <=27 Celsius
Dehumidification
15 mins of dehumidification when APU is operated for at least 30 mins. Set controllers to auto 2 dot and slowly to 3 dot.
