Instruction Manual

G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air Page 4-37
190-00915-01 Revision 8
4.17 Power Bus Check
4.17.1 Power Bus Feeder Check
This procedure will verify the availability of the feeders to the essential bus and the No.1 and No.2 dual
feed buses.
1. Apply external power. Turn BATT and AVIONICS MASTER switches to ON position. Verify all
circuit breakers are closed. Observe PFD1, PFD2 and MFD displays and verify all displays are
powered and in normal format. Verify the absence of red Xs or alert messages. Select, or verify
selected, on-side sensors for PFD1 and PFD2.
2. Open the ESS BUS PRI circuit breaker. Verify the MFD remains powered
3. Open the ESS BUS SEC circuit breaker. Verify the MFD is not powered
4. Close the ESS BUS PRI circuit breaker. Verify the MFD powers up.
5. Close the ESS BUS SEC circuit breaker.
6. Open the No. 1 dual bus feeder circuit breakers (RH NO.1, LH NO.1). Verify PFD1 FAN FAIL and
GIA1 FAN FAIL alert messages are shown on the PFD. If the messages are not shown, check the
dual-bus feeder circuit breakers (RH NO.1, LH NO.1) and the diode (CR1002) between No. 1 dual
feed bus and the essential bus. After replacement of the faulty component, the test should be
repeated.
7. Close No 1 dual bus feeder circuit breaker RH No 1. Verify PFD1 FAN FAIL and GIA1 FAN FAIL
alert messages are not shown on the PFD. If messages illuminates check dual bus feeder circuit
breaker RH No 1, associated limiter and diode.
8. Open No 1 dual bus feeder circuit breaker RH No 1.
9. Close No 1 dual bus feeder circuit breaker LH No 1. Verify PFD1 FAN FAIL and GIA1 FAN FAIL
alert messages are not shown on the PFD. If messages illuminates check dual bus feeder circuit
breaker LH No 1, associated limiter and diode.
10. Close No 1 dual bus feeder circuit breaker RH No 1.
11. Open No 2 dual bus feeder circuit breaker LH No. 2. Verify PFD 2 remains powered. If power to
PFD 2 is removed, check dual bus feeder circuit breaker RH No 2, associated limiter and diode.
12. Open No 2 dual bus feeder circuit breaker RH No 2. Verify PFD 2 is not powered.
13. Close No 2 dual bus feeder circuit breaker LH No 2. Verify PFD 2 powers up. If PFD 2 remains
without power, check dual bus feeder circuit breaker LH No 2, associated limiter and diode.
14. Close No 2 dual bus feeder circuit breaker RH No 2.
15. If no other service is to performed, remove aircraft power.
4.17.2 Dual Bus-Feeder Diodes Check
Supersedes King Air 200 Series Maintenance Manual 24-50-00 periodic inspection of dual bus feeder
diodes.
1. Remove aircraft power by turning BATT and AVIONICS MASTER switches to OFF position.
2. Remove all electrical power from the airplane.
3. Remove the center aisle floorboards and covers as necessary to gain access to the power distribution
panel (A145).
4. Remove the left isolation limiter (F131).