System- Auxiliary Power Unit

Question 1

APU maximum EGT?

Answer 1

743 ̊C

Question 2

APU maximum EGT for starting

Answer 2

974 ̊C

Question 3

Air condition in flight (APU)

Answer 3

Bleed air extraction from the APU is not permitted above 15,000 ft. MSL.

Question 4

Engine start during ground operations (APU)

Answer 4

• No bleed air extraction limitation
• Each engine may be started using the APU as a bleed air source
• If both engines are to be started using the APU bleed air, then the operating engine’s thrust must not exceed 70 % N2.

Question 5

Engine start during flight (APU)

Answer 5

• During single engine operations, APU bleed air extraction for an engine start is not permitted.
• During double engine failure conditions, APU bleed air extraction for engine starts is permitted; however, APU bleed air extraction is limited to 13,000 ft and below.

Question 6

The maximum load on the APU generator.

Answer 6

30 kVA.

Question 7

Minimum ambient temperature for starting APU

Answer 7

Minimum ambient temperature for starting a cold-soaked APU on the ground: -40 ̊C

Question 8

APU Start Cycles

Answer 8

1: GPU 15 sec. / Batt. 30 sec. | 2 min. off
2: GPU 15 sec. /Batt. 30 sec. | 20 min. off
3: GPU 15 sec. / Batt. 30 sec. | 2 min. off
4: GPU 15 sec. / Batt. 30 sec. | No further start attempts for at least 40 min.