Electrical System Flashcards
Draw the electrical system
See image
DC system voltage
28
DC power sources
Battery
Gen 1
Gen 2
Ext power
Generator voltage and amperage
28 VDC
200 amps
Starter Cycle Limits with fuel ignition
60 sec on 60 sec off 60 sec on 15 min off Repeat
Starter cycle limits without fuel ignition
30 sec on 30 sec off 30 sec on 15 min off Repeat
What is powered with the battery switch on?
Battery bus and essential bus
If the Essential Volts Low caution light and the Essential Bus recovery light are on with the battery switch and one generator operating what does that indicate?
Battery voltage is less than 24 +/- 0.5 Volts
Which inverter can be powered by the battery and how?
The #2 Inverter can be powered through the DC Ess Bus by turning on the battery switch and the #2 inverter switch.
What happens automatically when you plug in external power?
What happens when you turn on the external power switch?
The battery is isolated to the battery bus by the external power contactor.
The external power contactor allows the external power source to power the DC Ess bus and the Bus Tie Contactor allows the external power to power the rest of the electrical system.
What can happen during an external power start?
DECU can enter self test mode causing the loss of T5 and/or N1. Abort start.
Can a single generator power the entire system?
Yes
What does the bus tie contactor do?
Isolates the battery to the batt and DC Ess busses to prevent excessive draining.
Allows the battery to be charged.
Allows external power to power entire electrical system.
What happens when you activate the Essential Bus Recovery System?
The #1 generator is taken offline.
The #2 generator is connected to the DC essential bus through the Ess bus recovery contactor bypassing the faulty bus tie contactor.
The Air Cond is turned off.
What does the Ess Volts low light indicate?
The bus tie contactor has failed and the Ess bus has drained the battery to 24 +/- 0.5 volts or less.
What illuminates in conjunction with the Ess volts low caution light?
The Ess bus recovery light over the Ess bus recovery switch.
In the event of a dual generator failure, how long can the pilot’s pitot heat be used without affecting the 30 min night IFR usage? The search light?
Pitot heat for 5 min
Search light for 1 min on landing
What is lost if both inverters fail?
Complete AC electrical system including:
DAFCS
Compass and CDI portions of EHSI
What is the battery voltage and capacity?
24 V
42 AH
What are some items on the DC Ess Bus?
Landing Gear Search Light Fire Detection and Suppression IIDS Pilot EFIS #2 Radio #2 AP Stick trims Upper anti-collision light ICS DECU Radio and EFIS master switches
What is on the battery bus?
Tail rotor and intermediate gearbox viewing lights
Light in cockpit
What are the two voltages of the AC electrical system?
26 VAC
115 VAC
What should you do in electrical emergency?
R - reduce load
A - autopilots
T - transition to VMC
How many electrical busses are there?
8
DC essential
No 1 DC Primary
No 2 DC Primary
Battery
No 1 AC Primary
No 2 AC Primary
No 1 26 VAC
No 2 26 VAC
How do you access the electrical page on the IIDS?
Press menu, then elec
Which busses have current limiters? Can the pilot reset them?
DC Ess
No 1 DC Primary
No 2 DC Primary
No
Where are the AHRS circuit breakers located?
5-2-5
5 rows up from bottom on lower panel
2 rows up from bottom on upper panel
5 rows up from bottom on upper panel
What does the Generator Control Unit do?
Regulates generator output voltage (primary purpose)
Protects against over voltage, under voltage, reverse current and ground fault conditions.
What are the DC Junction box components?
No 1 and No 2 start contactors No 1 and No 2 generator contactors Bus tie contactor Master start contactor Battery contactor External power contactor External power interlock relay Three current limiters
What are the inverters rated at?
375 VA (watts)
115 and 26 VAC
400 Hz
Single phase
Where are the Buss tie circuit breakers located?
Right and left side of the upper row of the upper panel
