Diagnosing intermittent autopilot disconnects in a Dynon glass cockpit system involves a systematic approach to identify the root cause, which is almost always related to a wiring issue, power problem, or a faulty component. An intermittent disconnect is particularly challenging because it’s hard to replicate, often occurring due to a specific condition like vibration or a change in electrical load. The key is to analyze the system’s data logs to pinpoint the exact moment of the disconnect and then methodically inspect the relevant components.
Common Causes of Intermittent Autopilot Disconnects
The principle of consistency is vital here; the problem may be hard to reproduce, but it’s not random. There is an underlying cause that is consistently leading to the failure.
- Autopilot Disconnect Switch Wiring: The most common culprit is a wiring issue with the autopilot disconnect button. The Dynon system disengages the autopilot when the disconnect switch wire is grounded. A chafed wire that intermittently shorts to the airframe can be interpreted by the system as a manual disconnect command. This can also be caused by a faulty switch or a loose connection.
- Intermittent Power to Servos: The autopilot servos are the physical units that move the control surfaces. If either servo loses power, the autopilot will disconnect. This can be caused by a circuit breaker that is no longer working to specification, a loose wire in the power circuit, or a corroded connection that can’t handle the electrical load.
- Out-of-Trim Condition: While flying, if the aircraft is significantly out of trim, the autopilot servos must work harder to maintain the desired attitude. This can cause the servos to exceed their torque limits, leading to an automatic disconnect to prevent a servo over-stress condition.
- Data Bus Errors: The Dynon SkyView system communicates with its components, including the servos, via a data bus. A loose or damaged wire in this network can disrupt communication, causing the system to lose contact with the servos and disconnect the autopilot.
The Professional Diagnostic Process
The principle of authority dictates that this diagnosis must be performed by a certified avionics technician. At The Aero Center, we follow a methodical process to ensure a correct and lasting fix.
- Pilot Interview and Log Analysis: The first step is to get a detailed report from the pilot about the conditions under which the disconnect occurs. The technician will then download the system logs from the SkyView system. The logs are a goldmine of information, providing a detailed history of all system alerts, including the exact time and date of an autopilot disconnect event. The log will often indicate if the disconnect was caused by a manual command (the disconnect button) or a system error.
- Wiring and Connection Inspection: Based on the log analysis, the technician will meticulously inspect the wiring harnesses for any signs of chafing, loose pins, or corrosion. They will pay special attention to the autopilot disconnect switch’s wiring, as this is a frequent point of failure. A multimeter can be used to check for continuity and to see if the wire is intermittently shorting to ground.
- Power and Ground Checks: Using a Digital Multimeter (DMM), the technician will check the voltage and ground at the power inputs for the autopilot servos. They will run the system and simulate various flight conditions to see if they can replicate the intermittent power loss.
- Software Verification: The technician will ensure that all components in the Dynon system are running the same, most current software version. Mismatched firmware can cause communication errors that lead to intermittent problems.
The Aero Center’s Commitment
At The Aero Center, we understand that a grounded aircraft is a major inconvenience. Serving California, Arizona, and Nevada, our certified technicians have the specialized tools and manufacturer-specific knowledge to diagnose and repair your Dynon avionics system. We are the only 24/7 maintenance center in the area, a commitment that allows us to begin diagnosing your aircraft’s problem immediately, significantly reducing your downtime. Our goal is to provide a swift, accurate, and reliable fix, getting you back in the air with confidence.
Footnotes
- Dynon Avionics, “SkyView System Installation Guide,” Dynon Avionics, 2024. https://www.dynonavionics.com/includes/guides/SkyView_System_Installation_Guide-Rev_R.pdf
- AviationPros, “Troubleshooting Glass Cockpit Displays,” AviationPros, 2020. https://www.aviationpros.com/aircraft-maintenance-technology/avionics-systems/article/21151608/troubleshooting-glass-cockpit-displays
- AOPA, “Avionics Upgrades and Maintenance,” Aircraft Owners and Pilots Association, 2024. https://www.aopa.org/go-fly/aircraft-and-ownership/avionics
The Aero Center is located at William J. Fox Airfield KWJF | Lancaster, CA. Contact us at 209.885.6950 for questions or appointments.