Instruction Manual

G1000 / GFC 700 System Maintenance Manual - 300/B300 Series King Air Page 4-29
190-00716-01 Revision 3
4.13 G1000 Miscompare Checks
This procedure will check the AHRS, airspeed and altitude miscompare monitors. Accomplish the
following checks with the aircraft positioned where it can receive GPS signals and magnetic heading.
Access to AHRS1 and AHRS2 will be required during this test.
1. Ensure the G1000 is operating in normal mode.
2. Connect a pitot/static test set to the aircraft ADC1 pitot and static ports (Pilot’s side). (Do not connect
the pitot/static tester to ADC2 ports at this time.)
3. Set the baro-correction on PFD1 and PFD2 to 29.92.
4. On the AFCS mode controller, press the ALT, HDG, and AP buttons and verify autopilot engages.
5. Slowly increase the pitot/static test set to simulate an ADC1 / ADC2 altitude miscompare of greater
than 200 ft., verify the disconnected ADC altitude does not increase, autopilot does not disconnect
and amber comparator window text “ALT MISCOMP” is displayed on PFD1 and PFD2.
6. Reduce ADC1 altitude to ambient pressure.
7. Repeat Step 5 with the pitot/static test set connected to the aircraft ADC2 pitot and static ports.
8. Use the pitot/static test set to simulate an airspeed of 40 kts for ADC1 and 55 kts for ADC2. Verify
the autopilot does not disconnect and amber comparator window text “IAS MISCOMP” is displayed
on PFD 1 and PFD2.
9. Use the pitot/static test set to simulate an airspeed of 55 kts for ADC1 and 40 kts for ADC2. Verify
the autopilot does not disconnect and amber comparator window text “IAS MISCOMP” is displayed
on PFD 1 and PFD2.
10. Use the pitot/static test set to simulate an airspeed of 85 kts for ADC1 and 95 kts for ADC2. Verify
the autopilot does not disconnect and amber comparator window text “IAS MISCOMP” is displayed
on PFD 1 and PFD2.
11. Use the pitot/static test set to simulate an airspeed of 95 kts for ADC1 and 85 kts for ADC2. Verify
the autopilot does not disconnect and amber comparator window text “IAS MISCOMP” is displayed
on PFD 1 and PFD2.
12. Reduce ADC1 and ADC2 airspeeds to 0 kts.
13. Slowly rotate AHRS1 along the lateral (pitch) axis to a pitch attitude of greater than 5 degrees, verify
the following:
• AHRS2 pitch attitude does not change
• An amber “PIT MISCOMP” is annunciated on PFD1 and PFD2
• Autopilot disconnects at approximately 5 deg AHRS1 / AHRS2 miscompare
• The autopilot disconnect audio alert (two hi-low tones) sounds
• A red flashing AP annunciator on PFD1 and PFD2
• Flight director command bars remain in view with autopilot in HDG and ALT mode
14. Replace AHRS1 to normal attitude and verify that attitude display on PFD1 displays current aircraft
attitude.
15. Use the AFCS mode controller to re-engage autopilot.