Electrical

Question 1

What is the maximum battery load meter reading for takeoff?

Answer 1

0.1

Question 2

What is the minimum battery temperature for takeoff?

Answer 2

-20° C

Question 3

After starter reset, when can you commence the start procedure for the other engine?

Answer 3

Main battery load less then .40, and starter select light extinguished

Question 4

Under what conditions may the APU be used for engine starts even though a GPU is available?

Answer 4

For engine start if:

• The APU is already operating (for bleed air, etc.)
• Engine starts at the gate are prohibited (e.g., airport restrictions)
• Engine start at the gate will delay or be delayed by passenger boarding of an adjacent aircraft

FOM 3.1.21

Question 5

What is the definition of blocking out for maintenance purposes?

Answer 5

For the purpose of this section, the term “block(ing) out” is defined as movement of the aircraft under its own power for the purpose of flight. The term “block(ing) in” is defined as parking the aircraft at the completion of flight or upon return to the gate.

FOM 11.3.9

Question 6

What are the Primary Power Source Caution Lights when there are multiple amber caution lights illuminated? Why do we need to know what they are?

Answer 6

Primary power source caution lights are: 
#1/#2 ENG HYD PUMP 
#1/#2 DC GEN 
#1/#2 AC GEN 

Some conditions result in multiple amber caution messages. When multiple lights are illuminated, the light associated with the primary power source for that system should be called.

FSM 2.1.3

Question 7

Can we reset/pull circuit breakers without direction from an emergency/abnormal checklist or maintenance control?

Answer 7

No

Question 8

Approximately how long should the batteries last when on essential power?

Answer 8

60 Minutes

Question 9

List a combination of failures that would cause the EPCU (Electrical Power Control Unit) to enter emergency mode?

Answer 9

Both TRUs and one DC generator fails

Question 10

What systems are powered by the 115 volt AC busses?

Answer 10

· De-icing/Anti-icing heaters
· Standby Hydraulic pump (#1 Hydraulic System)
· Transformer Rectifier Units (TRU)
· #1 and #2 Auxiliary Fuel pumps

SDM 6-16

Question 11

Can you provide external DC power and APU DC Gen power to the DC Buses at the same time?

Answer 11

No

With external power connected and the external power toggle switch set to the EXT PWR position, the EPCU will remove APU electrical power and allow the GPU to power the DC buses.

SDM 6-10

Question 12

Does a green “DC EXT PWR” message displayed on the MFD electrical page indicate that the aircraft is receiving 28V from the GPU?

Answer 12

A DC EXT PWR message (green) is displayed in the top left corner of the MFD Electrical page when the DC EXT PWR switch is ON and the aircraft is receiving external DC power.

To verify 28 VDC you have to check the buss loads on the electrical page

SDM 6-8

Question 13

How can you verify that 28V DC power is being received from the GPU?

Answer 13

Electrical page

Question 14

Will a APU GEN overheat cause the APU to shut down?

Answer 14

Yes