Instruction Manual

Page 4-40 G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air
Revision 9 190-00915-01
7. By observing the following annunciators, power to each of the four buses will be verified: L FUEL
PRESS, R FUEL PRESS, L BL AIR FAIL and R BL AIR FAIL. If any of the annunciators fail to
illuminate, the associated limiter (F148, F149, F150 or F154), one of the four dual-bus-feeder diodes
(CR2) or dual-bus circuit breakers (RH NO. 1, RH NO. 2, RH NO. 3 or RH NO. 4) is open. If failure
of an annunciator is apparent, reset or replace the faulty component and repeat the test.
8. Units on the No. 1 avionics bus SHOULD NOT operate. Verify COM 2 is not powered by observing
a red X is displayed in COM 2 tuning window. If COM 2 is powered, at least one of the dual-bus-
feeder diodes is shorted. Detection of the shorted diode (diodes) may be accomplished by opening the
following dual-bus-feeder circuit breakers: (LH NO. 1, LH NO. 2, LH NO. 3 or LH NO. 4). After
replacement of the shorted diode (diodes), the test should be repeated.
9. Remove all electrical power from the airplane.
10. Reinstall the left isolation limiter (F131). Remove the right isolation limiter (F132).
11. Apply external power. Turn BATT and AVIONICS MASTER switches to ON position
12. Bus voltage SHOULD be present on the left isolation bus (W108). Units on the No.1 avionics bus
SHOULD operate. Verify COM 2 is powered by observing a frequency is displayed in COM 2 tuning
window. Operation of COM2 will verify continuity of the left isolation limiter (F131).
13. By observing the following annunciators, power to each of the four buses will be verified: L FUEL
PRESS, R FUEL PRESS, L BL AIR FAIL and R BL AIR FAIL. If any of the annunciators fail to
illuminate, the associated limiter (F145, F146, F147 or F153), one of the four dual-bus-feeder diodes
(CR1) or dual-bus circuit breakers (RH NO. 1, RH NO. 2, RH NO. 3 or RH NO. 4) is open. If failure
of an annunciator is apparent, reset or replace the faulty component and repeat the test.
14. The GDL 69A SHOULD NOT operate. Verify that the GDL69 FAIL alert message IS shown on the
PFD. If the GDL 69A DOES operate, at least one of the dual-bus-feeder diodes (CR2) is shorted.
Detection of the shorted diode (diodes) may be accomplished by opening the following dual-bus-
feeder circuit breakers: (LH NO. 1, LH NO. 2, LH NO. 3 or LH NO. 4). After replacement of the
shorted diode (diodes), the test should be repeated.
15. Remove all electrical power from the airplane.
16. Reinstall the right isolation limiter (F132).
4.18 Exterior Skin Inspection Around Antennas
Perform a visual inspection of the exterior skin for cracks and loose and missing fasteners in an area at
least 1-inch around the following antennas:
• GA 36 GPS antenna
• GA 37 GPS/XM antenna
• GA 58 Traffic Antenna, Upper (if Garmin traffic system is installed)
• GA 58 Traffic Antenna, Lower (if Garmin traffic system is installed)
• Transponder Antenna, Upper #1 (if Garmin GTX 33D or GTX 3000 transponder is installed)
• Transponder Antenna, Upper #2 (if Garmin GTX 33D or GTX 3000 transponder is installed)
• Iridium Antenna (if Garmin GSR 56 satellite receiver is installed)
• Wi-Fi Antenna (if Garmin GDL 59 wi-fi data link is installed)
The antennas do not need to be removed to perform this inspection.