Page 5-32 G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air
Revision F 190-00682-01
Annunciation Condition Resolution
Aileron Mistrim
Right
• Check for possible fuel imbalance.
• Check aileron control adjustments.
• If mistrim condition still exists remove and replace the roll
servo.
Aileron Mistrim
Left
Rudder Mistrim
Right
• Check rudder control adjustments.
• If mistrim condition still exists remove and replace the yaw
servo.
Rudder Mistrim
Left
Pre-Flight Test
Fails
• Allow the system to complete pre-flight tests.
• The preflight test should finish within 2 minutes. If it does
not pass, the red ‘PFT’ annunciation is shown. In case of
PFT failure, see Section 5.6.5 for additional PFT diagnostics.
Table 5-4. AFCS General Troubleshooting
Condition Resolution
Poor AP Performance
(Limited AP Authority)
• Check each servo mount slip clutch per Section 4.9. Verify
the clutches are not excessively loose and are within
torque limits.
• Check aircraft controls for proper adjustment per the King
Air Model 90 Series Maintenance Manual.
• Check aircraft control cables for proper tension per the
King Air Model 90 Series Maintenance Manual.
AP DISC Problems
• For intermittent nuisance disconnects with no AFCS of PFT
alert, check A/P disconnect switch and wiring for
intermittent faults.
• If an AFCS or PFT alert is displayed at the time of the
disconnect, troubleshoot per Section 5.5.
• Check the GIA AFCS Fault Logs according to Section
5.6.4. If a Mon Prmtr Invalid message is received, check
for valid true airspeed. A faulty GTP 59 OAT probe may
cause TAS to become invalid, which will flag the
Mon Prmtr Invalid message.
• Contact Garmin Product Support for assistance
Loss of Manual Electric Trim
• Check pitch trim servo status.
• Check MET switch discrete inputs to both GIAs by going to
the GIA I/O Configuration page and selecting DISCRETE
IN inputs.
AutoTrim Inoperative
• Check flap-in-motion discrete inputs to both GIAs for proper
operation by going to the GIA I/O Configuration page and
selected DISCRETE IN inputs. See Section 4.8.
• If DATA indicator fails to illuminate or illuminates
incorrectly, troubleshoot flap motor & discrete input wiring
(refer to G1000/GFC 700 Wiring Diagram, listed in Table
1-2).
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