King Air Autopilot Troubleshooting

August 2009

If your autopilot is not performing as well as it once was, there are a few quick items you can easily check.

If your King Air has an AP-105 system and is exhibiting symptoms of "loose" altitude hold, it may be time to take a look at your 590A-3( ) altitude control sensor. The 590A-3H sensor is a motor-driven gear train that with time wears and causes altitude hold "bumps," or intermittent pitch excursions, when altitude hold mode is engaged. This can also cause altitude preselect capture overshoots. 

Another common squawk is porpoise in altitude hold mode. If your system has a 590A-3K1 installed, even though it does not have a mechanical gear train like the 590A-3H, it can cause the same symptoms.

Of course this is only one of the components that can cause degraded autopilot performance. Feel free to call a Duncan Aviation Components Tech Rep with your symptoms and we will help you to determine the most likely cause.

King Air Technical Support

Campbell, Curt - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1975. Airframes: Challenger, Hawker, Learjet, King Air, Global Air Data Computer, Auto Pilot Systems, EFIS, Roll Modules, Mode Couplers and Selectors, Static Inverters, Servos, Spoiler System, Tool Calibration Lab, Flight Guidance Computer, Cabin Displays, and EFD Components and Systems Specialist. Direct: 402.479.4220 Mobile: 402.416.8832

Magnus, Dan - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1976. Airframes: Citation, Embraer, Gulfstream, Hawker, King Air ADF, Comms, Control Heads, CVR, DME Gables Control Heads, Receivers, Nav-Comm/Receivers, Radar Systems, GPS, GNS, Transponders and UNS Components and Systems Specialist. Direct: 402.479.4217 Mobile: 402.416.1870

Schultz, Gerry - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1965. Airframes: Hawker, King Air Instrumentation, Vertical and Directional Gyros, Airspeed Indicators, HSI, ADI, Encoders, Course Indicator, Rate Gyro, Directisyn, Vertisyn, RMI and Pitot Static Components and Systems Specialist. Direct: 402.479.4212 Mobile: 402.416.4742

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