APU Flashcards
Question: What is the MAX starting Altitude for the APU?
Answer: Guaranteed to start < 37,000
Question: What are the APU starting attempts limitations?
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: What is the MAX operating Altitude for the APU?
Answer: Up to 45,000
Question: When starting the APU would there be a delay in the release of APU bleed air?
Answer: On the GROUND YES 60 seconds if EGT is >149C. INFLIGHT NO
Question: Getting ready to taxi out, you select the APU to STOP, what are you expecting to happen?
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: If the APU is running and the Right Cowl Door is OPENED will the APU continue to RUN?
No
Question: Would the APU shut down any differently at altitude?
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: Can APU air be used inflight?
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: What power sources can be used for starting the APU?
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: Where does the APU normally get its fuel from?
Answer: Left side motive fuel line (Left Hopper).
Question: What are APU’s two on-speed modes?
Answer: NON-ESSENTIAL if on ground and ESSENTIAL in-flight
Question: What’s the indication that air inlet door has opened and APU is ready to start?
Answer: Cyan “APU Ready” annunciation illuminates on IRS / APU / Batt page of OHPTS’s and READY light on the APU Control Master Switch
Question: After selecting the APU Master ON the switch indicates amber FAULT. Can you clear this indication?
Answer: Yes, Cycle MASTER and try again
Question: Inflight you get an amber APU Essential CAS message. What does that indicate?
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: Once on the ground how many minutes will the APU continue to operate if operating in APU Essential mode?
Answer: 15 Minutes
Question: Is APU air available immediately upon APU start? On Ground: Cold Aircraft (APU EGT < 149° C)
No
Inflight:
Answer: YES (For Engine Assisted STARTS – Controlled by the FADEC)
Question: What happens if the APU START/STOP switch is depressed anytime during the 60 second cool down period?
Answer: APU is commanded to 100%.
Question: What are a FEW of the embedded (automatic) features that occur when APU Master Switch is selected ON?
Answer: 1. TROV opens;
- Left main Fuel Boost Pump turns on;
- Navigation Lights turn on;
- annunciation illuminates on IRS / APU / Batt page of OHPTS’s and the APU Control Master Switch
Question: Where can you find the TYPES of oil used in the engines or APU?
Answer: OM, Handling and Servicing Procedures, Servicing Fluids and Additives, Engine and APU oil Grades.
Question: The APU is inoperative or cannot be used to start an engine, what is the maximum altitude the aircraft can operate?
Answer: At or below 30,000 feet
