APU

Question 1

Question: What is the MAX starting Altitude for the APU?

Answer 1

Answer: Guaranteed to start < 37,000

Question 2

Question: What are the APU starting attempts limitations?

Answer 2

MAX of 3 start attempts with a cool down of 1 minute between each attempt.

THEN

After the THIRD attempt must wait 1 hour before another attempt.

Question 3

Question: What is the MAX operating Altitude for the APU?

Answer 3

Answer: Up to 45,000

Question 4

Question: When starting the APU would there be a delay in the release of APU bleed air?

Answer 4

Answer: On the GROUND YES 60 seconds if EGT is >149C. INFLIGHT NO

Question 5

Question: Getting ready to taxi out, you select the APU to STOP, what are you expecting to happen?

Answer 5

Answer: The APU ECU sheds the APU Generator and Bleed Air. Surface to 20,000 feet the APU slows down at 1/2 % per second to 70% then shuts down.

Question 6

Question: If the APU is running and the Right Cowl Door is OPENED will the APU continue to RUN?

Answer 6

No

Question 7

Question: Would the APU shut down any differently at altitude?

Answer 7

Answer: Above 20,000 feet the APU sheds the APU Generator and Bleed Air and operates at 100% for 1 minute before shutting down.

Question 8

Question: Can APU air be used inflight?

Answer 8

Answer: Yes, for engine starts 30,000 feet and below.

The FADEC can OPEN the APU Load Control Valve if no other bleed air is available for Engine Assisted Starts

Question 9

Question: What power sources can be used for starting the APU?

Answer 9

Answer: Left Ships Battery to Start, Right Ships Battery for APU ECU.

Can Start with JUST the Right Ships Battery.

External AC Power - AFM 02-06-10 APU Restricted (EXT PWR) Start Use of an External DC power source to start the APU is prohibited

Question 10

Question: Where does the APU normally get its fuel from?

Answer 10

Answer: Left side motive fuel line (Left Hopper).

Question 11

Question: What are APU’s two on-speed modes?

Answer 11

Answer: NON-ESSENTIAL if on ground and ESSENTIAL in-flight

Question 12

Question: What’s the indication that air inlet door has opened and APU is ready to start?

Answer 12

Answer: Cyan “APU Ready” annunciation illuminates on IRS / APU / Batt page of OHPTS’s and READY light on the APU Control Master Switch

Question 13

Question: After selecting the APU Master ON the switch indicates amber FAULT. Can you clear this indication?

Answer 13

Answer: Yes, Cycle MASTER and try again

Question 14

Question: Inflight you get an amber APU Essential CAS message. What does that indicate?

Answer 14

Answer: It means it hasn’t shutdown for one of the malfunctions that would have caused shutdown on ground. Don’t shut it down if you really need it because a subsequent start may be inhibited. If you don’t need it, shut it down by pressing APU STOP and then APU MASTER

Question 15

Question: Once on the ground how many minutes will the APU continue to operate if operating in APU Essential mode?

Answer 15

Answer: 15 Minutes

Question 16

Question: Is APU air available immediately upon APU start? On Ground: Cold Aircraft (APU EGT < 149° C)

Answer 16

No

Inflight:

Answer: YES (For Engine Assisted STARTS – Controlled by the FADEC)

Question 17

Question: What happens if the APU START/STOP switch is depressed anytime during the 60 second cool down period?

Answer 17

Answer: APU is commanded to 100%.

Question 18

Question: What are a FEW of the embedded (automatic) features that occur when APU Master Switch is selected ON?

Answer 18

Answer: 1. TROV opens;

2. Left main Fuel Boost Pump turns on;
3. Navigation Lights turn on;
4. annunciation illuminates on IRS / APU / Batt page of OHPTS’s and the APU Control Master Switch

Question 19

Question: Where can you find the TYPES of oil used in the engines or APU?

Answer 19

Answer: OM, Handling and Servicing Procedures, Servicing Fluids and Additives, Engine and APU oil Grades.

Question 20

Question: The APU is inoperative or cannot be used to start an engine, what is the maximum altitude the aircraft can operate?

Answer 20

Answer: At or below 30,000 feet