APU

Question 1

What Type of APU is installed in the G7500?

Answer 1

SPU300

Question 2

What is the APU Maximum RPM?

Answer 2

APU Maximum RPM: 105%.

Question 3

What is the APU max EGT for Start and Normal Operation?

Answer 3

• Max Start EGT: 1032° C;
• Normal Operation EGT: 718°C.

Question 4

What is the Maximum Altitude for APU Generator operations?

Answer 4

APU Generator 51,000 ft.

Question 5

What is the Maximum Altitude for Starting the APU in flight?

Answer 5

APU Start 45,000 ft.

Question 6

What is the Maximum Load rating for the APU? (FCOM 2 Electrical)

Answer 6

• 60 KVA up to 45,000 ft without restriction
• 40 KVA above 45,000 ft.

Question 7

If acft above FL 430, APU Generator provides power to how many ACMP?

Answer 7

• Above 43,000, APU Generator will provide power to 1 HYD ACMP only.

Question 8

What is the Maximum Altitude for Bleed Air extraction from the APU?

Answer 8

• APU provides for ECS Bleed 25,000 ft.

Question 9

What is the Maximum Altitude to assist an Engine Start with the APU?

Answer 9

• Engine Start Assist by APU is 23,000 ft

Question 10

What’s the average APU fuel consumption per hour?

Answer 10

Average 240 lbs/Hr (4 lbs/min).

Question 11

What is the minimum temperature for starting a cold soaked APU on the ground?

Answer 11

Cold Soaked APU Start on the ground: - 40°C.

Question 12

What is the Maximum OAT for Bleed Air extraction on the ground for A/C operations?

Answer 12

• Maximum OAT for Bleed Air Extraction: +48°C.
  Note: For landing, start APU before in order to have electrical available on the ground (close the bleed).

Question 13

How many Start Attempts are permitted on the APU?

Answer 13

Maximum 3 Attempts per Hour.

Question 14

When does the APU Door Position appear on the EICAS and the Service Synoptic?

Answer 14

• If the door is not in the commanded position;
• Note: An Amber “APU DOOR FAIL” CAS message also comes on.

Question 15

When is Manual operation of the APU BCV (Bleed Control Valve) not possible?

Answer 15

• 1. Anti-Ice is Active;
• 2. LH Engine PRV (Pressure Regulating Valve) is manually opened;
• 3. RH Engine PRV (Pressure Regulating Valve) & the Crossbleed Valve are manually opened.

Question 16

Which Fuel Pump supplies Fuel pressure to the APU during Start?

Answer 16

• When AC power is not available, the Right Auxiliary DC Pump in the collector tank supplies fuel pressure;
• When AC power becomes available from the APU Generator or another source, the Right Primary AC Fuel
  pump (in the right Collector Tank) starts, and the Right Auxiliary DC pump shuts down.

Question 17

Can you Dispatch with the APU Door Failed Open? (DDG)

Answer 17

• Yes, with restrictions.
• Note: the primary issue is the APU windmilling without lubrication.

Question 18

What conditions must be met before using the Oil Replenishing System for the APU?

Answer 18

• APU has been Shutdown for a Minimum of 10 minutes;
• Minimum OAT: -12°C.

Question 19

What component of the APU prevents an APU Compressor from Stall occurring in the flight?

Answer 19

SCV (Surge Control Valve)

Question 20

What happens to the APU BCV (Bleed Control Valve) if the APU is pressurizing the pneumatic manifold, and
then the Left Engine Bleed Valve opens?

Answer 20

• The APU BCV automatically closes;
• Interlock Protection: The BMC control logic ensures the APU BCV cannot be opened when another bleed
  source is supplying the bleed air manifold.

Question 21

What happens when APU Fire is detected on the ground?

Answer 21

• The APU automatically shuts down, and if no crew action is taken within 10 seconds, BTL 2 discharges into
  the APU enclosure.

Question 22

How is an Emergency Shutdown of the APU accomplished?

Answer 22

• 1. Pressing the APU FIRE PBA;
• 2. Pushing the APU SHUTOFF button on the Aft Service Panel;
• 3. Pushing the Red APU Shutdown switch in the APU compartment.

Question 23

What is the sequence of actions when an APU FIRE PBA is pressed?

Answer 23

• 1. APU Emergency Shutdown is triggered;
• 2. APU Fuel FSOV (Fire Shutoff Valve) closes;
• 3. APU Hyd SOB closes;
• 4. APU BCV closes;
• 5. APU Generator Turns OFF;
• 6. BTL 2 arms.