APU Flashcards
Max load on the APU generator?
40 KVA
Max altitude for APU starting?
37,000 ft
Max altitude for APU operation?
41,000 ft
Max altitude for APU bleed air extraction?
25,000 ft
Max speed with APU door open?
220 KIAS if APU not operating
No speed restriction when operating
What battery voltage is required before starting the APU?
22 volts on both batteries
What does the Main Battery power during APU start?
APU ECU
What does the APU Battery power during APU start?
Cranking the 28 VDC start motor
When the AVAIL switchlight illuminate?
99% rpm + 2 seconds
The APU’s primary function is what?
To power the 40 KVA generator mounted on the gearbox
What does the APU door provide air for?
compressor & air/oil heat exchanger
How is the APU door actuated?
Electrically
Where does the APU receive fuel from?
Left collector tank
What is the electrical power source for the ECU?
The starter?
Battery Bus
APU Battery Direct Bus
What is the max rpm the starter will cutout by?
60%
Start Attempts (on ground)
1
2
3
Max Time on—-Cool Down
ECU —-30 secs
ECU —-30 secs
ECU —-1 hr
Start Attempts (in flight)
1
2
3
Max Time on—-Cool Down
ECU —-1 min
ECU —-1 min
ECU —-1 hr
Was the APU designed to run unattended during ground operations?
Yes
What is the rpm overspeed that will auto shutdown the APU?
> 106%
What valve opens to allow bleed air to the engines & PACKS?
LCV (load control valve)
Max altitude for main engine starting with APU?
Using the APU for A/C?
25,000 ft
25,000 ft
If APU door is open in flight with the APU off, slow the airplane down until the rpm is ___.
<12%
