Electrical Flashcards
Question: What is the lowest power source that will operate the Standby Flight Display?
Answer: Emergency Batteries L EMER DC R EMER DC
Question: What is the purpose of Emergency Batteries (EBATTS)?
Answer: They power emergency avionics and egress lighting.
Question: If operating on the Emergency Batteries ONLY do you have Air Data Information?
No
Question: What would have to be powered to get Air Data to the SFD?
Answer: ESSENTIAL DC power
Question: I press the ARM switch IN and E-BATT’s come ON. Why?
Answer: Senses less than 20 volts on the Essential Busses.
Question: What would I expect to see powered under this condition?
Answer: 1.SFD (Both)
2.TSC 2&3
- Emergency Exit Lights
BATTERY switches are now Pressed IN :***
Question: What additional screens would be powered?
Answer:
1. All 5 TSC
- DU 1 & 4
- OHPTS 1 & 2
Question: The “ON” lights are illuminated inside the battery switches. Why?
Answer:
1. Battery is powering the DC Essential Buses
- Aux Hyd. Pump is operating
- APU starting
Question: Can I use an external DC power cart to start the APU?
Answer: No
Question: When switching from AC External Power to APU Generator Power, will there be a no break power transfer or a break power transfer?
Answer: Break power transfer because the APU generator is not an IDG, there is no way to “sync” the power, so there will be a break power transfer.
Question: How should the electrical panel be configured for aircraft power up?
Answer: 1. All 4 generator switches In 2. BUS TIE switches OUT
Question: What is the purpose of GCUs?
Answer: Provide Quality of Power.
Question: How can a GCU be reset?
Answer: By cycling associated generator control switch (L GEN, R GEN, APU GEN, RAT GEN) to OFF for 5 seconds and then ON. This action causes the software to re-initialize.
Question: To ensure you get a NO break power transfer between AC power sources, what must you do?
Answer: Have an IDG involved.
Question: What causes the “AC” legend of AC/DC RESET switchlight to activate?
Answer: A Fault in Main AC or Emergency AC bus, a logic fault within BPCU, or by a relay or component failure (Glitch, Fault, Failure).
Question: If both AC and DC external power is connected, which has priority?
Answer: External AC
Question: Describe the purpose of the fifth or Aux TRU?
Answer: It serves as a backup to the other TRU’s.
When not serving in a backup role, the Aux TRU powers the Aux DC bus which provides 28 VDC power to cabin loads.
Question: What is the function of the EBHA battery?
Answer: It is a dedicated source of power to Electric Backup Hydraulic Actuators and Motor Controls Electronics (MCE).
Question: What is the purpose of the UPS battery?
Answer: It is a dedicated source of power to Flight Control Computers (Channels 1A and 2B), BFCU, 1 of 2 power sources of REUs.
Question: What does the RAT power?
Answer: L & R Ess TRU – Left and Right ESS Buses Emergency AC Bus EBHA battery charger, UPS battery charger, H-STAB Channel 1, L & R Side Window Heat,
Question: What are the sources of power for the ground service bus?
Answer: Right main DC bus, external DC power cart, or right battery.
Question: When will the Ground Service bus automatically deactivate?
Answer: When ALL doors are closed (Main Entrance Door, Tail Compartment Door, Security / Ground Service Door, & Refuel Panel Door)
Question: What powers the Emergency AC Bus?
Answer: Left Main AC or RAT generator.
Question: What happens on a dark airplane when the GND SVC BUS switch on the Security / Gnd Svc panel is selected to ON?
Answer: The right battery powers the ground service bus and the anti-collision beacon illuminates and TSC #5 is powered.
Question: How many TSC’s can be used to simultaneously control the SSPC’s?
Answer: The Secondary Power Distribution System can be accessed from any two of TSC 2 thru 5. Secondary Power is not available on TSC 1.
Question: You have deployed the RAT due to a dual generator failure. What is the Minimum speed for operation of the RAT generator?
200 kts
Question: When an engine fails, what directs the operating generator to power the effected GEN bus?
BPCU
Question: How would the EMERGENCY AC BUS receive power if the Left Main AC Bus failed?
RAT
Question: If the Right Essential TRU fails, what will power the Right Essential DC bus?
Answer: Aux TRU
Question: If we had a subsequent failure of the Left Essential TRU, what will occur?
Answer: Aux TRU will take over the Left ESS DC bus and the Right Ess DC bus will be powered by the BATTS.
Question: If you had to deploy the RAT. What buses can it power?
Answer: Emergency AC Bus
Left and Right ESS Buses
Question: You are departing from an airport that prohibits you from starting your APU until 10 minutes before your scheduled departure time, your aircraft is currently using an AC electric cart for electrical power. If you start the APU and it’s generator switch is IN would there be a Break Power transfer?
Yes
Question: Utilizing which checklist would prevent this?
Answer: APU Restricted (EXT PWR) Start
