APU

Question 1

What is the power source for the APU boost pump?

Answer 1

24-28V DC (battery)

Question 2

What systems does the APU indirectly supply?

Answer 2

Hydraulics and Generators

Question 3

What is the Nr range to avoid during APU operation?

Answer 3

94-96%

Question 4

What is the maximum number of APU start attempts permitted in one hour?

Answer 4

3

Question 5

What precaution is to be taken for when unauthorized personnel will be in the cockpit?

Answer 5

Pop the APU circuit breaker (right EFAB)

Question 6

What is the only APU warning?

Answer 6

APU fire

Question 7

What is the only APU caution?

Answer 7

APU on

Question 8

Where does the APU receive fuel from?

Answer 8

AFT fuel cell

Question 9

APU oil level is found where?

Answer 9

The sight glass

Question 10

When is APU bleed air provided?

Answer 10

Once APU reaches 95%

Question 11

Where is the APU located?

Answer 11

Inboard of the right engine nacelle in the aft equipment bay under a Kevlar enclosure

Question 12

What is the approximate fuel burn for the APU per hour?

Answer 12

175 lbs/hour

Question 13

What three things does the APU enclosure provide for the APU

Answer 13

1. Allows cool air to flow across the APU for cooling
2. The inlet screen is used to allow ambient air to be used for combustion
3. Confines the APU in the event of fire for extinguishing purposes

Question 14

What does the APU electronic control unit provide?

Answer 14

Provides for operational sequencing control for automatic starting PTO clutch operation, normal operations and APU operation

Question 15

What does the PTO clutch provide?

Answer 15

Provides the coupling and de-coupling between the APU and the main XMSN accessory gearbox, through the number 7 driveshaft

Question 16

Where is the APU oil level sight gauge located?

Answer 16

Right side of the APU and can be viewed through the access port on the bottom of the number two engine nacelle

Question 17

When viewing the APU oil level where should the oil level be on the sight gauge

Answer 17

The ball bearing should be midway on the sight gauge

Question 18

The APU is divided into two major sections what are they?

Answer 18

Accessory section and power turbine section

Question 19

The PTO clutch normally engaged when the APU reaches what percent?

Answer 19

Engaged at 60% APU speed

Question 20

During cold weather operation with the XMSN oil temp below 0 F when will the PTO clutch engage?

Answer 20

Will engage at 95% APU speed

Question 21

The load control valve will open at 95% APU SPEED and will REMAIN OPEN UNTIL WHAT TWO ACTIONS OCCUR?

Answer 21

The APU is shutoff or the fire/RDY push button is activated for the fire extinguisher system

Question 22

Where are the APU push buttons located?

Answer 22

Pilot power quadrant control panel

Question 23

What is the minimum aircraft requirements that must be present prior to starting APU?

Answer 23

Battery or external power
Minimum of 2600 PSI hyd pressure in utility hyd accumulator
Fuel in the aft fuel cell
APU oil level half full

Question 24

What is the maximum oil XMSN oil temp (on sys page) before APU must be turned off ?

Answer 24

The maximum oil temp for XMSN oil is 140c

Question 25

What systems does the APU directly supply?

Answer 25

Directly provides air to the Integrated Pressurized Air System (IPAS) and engines.

Question 26

What is the APU shaft power output?

Answer 26

Shaft power output: 81 Shaft Horsepower (SHP).