APU Flashcards
Fuel burn
120lb/hr
How much oil does the APU hold
3 quarts
Can you use the sight glass to check the oil level?
No, use the dipstick
When may you use the cold side of the APU oil dipstick?
When the APU is cold to the touch
How is the APU Generator cooled?
Air cooled
APU temp limit to _____ for _____ minutes with rotors __________
43 for 30 minutes with rotors and engine operating
APU Temp limit to _______ with rotors ___________
51 with rotors and engine not operating
What does do if APU oil hot caution appears.
Shut down APU immediately, 30 minute cooling period required before checking oil
What is the ESU, whats it do?
Electronic sequence unit
-Sequences the start procedure for the APU and monitors its operation.
-Will shut down the APU for any detected problems other than APU OIL HOT Caution
-APU FAIL appears anytime ESU auto shuts down the APU
If you get an APU fail, what dont you do?
Dont turn APU CONT switch on or turn BATT 1/2 off until after checking ESU BITE indicators
What are ESU BITE indicators?
Built in test equipment indicators
-Magnetically latched fault indicators
-4 dots, filled or unfilled in sequence
-Box has a decal decoding what all the combos of dots mean
Whats the difference between the DESU and the ESU?
DESU has 5 dots, operates electronically
How do you emergency override a DESU?
Cycle APU Start switch 5 times within 5 seconds
What are the limitations of operating the APU in emergency start override mode?
-DESU remains in emergency mode for max 2 minutes, after which time APU reverts to normal mode
-If original fault causing APU FAIL exists, APU will once again shut down.
-Can mask all fault conditions except
Overspeed
Underspeed
Short during start
Fuel faults
minimum APU accumulator pressure
2800
