Servicing power inverters that feed glass cockpit electronics in piston planes is a critical task that ensures the reliability and safety of the aircraft’s avionics. The inverter’s primary job is to convert the aircraft’s DC power to AC power, which is often required for older gyros or for the backlighting of certain displays. A failing inverter can cause display flickering, dimming, or complete failure. The following outlines the key steps in a professional service procedure.
Diagnosis of Inverter Failure
The principle of consistency is crucial in diagnosing an inverter failure. The technician will first perform a series of checks to rule out other possible causes of the display issue. The most common symptoms of an inverter failure are:
- Display Flickering: An unstable voltage output from the inverter can cause the display to flicker, particularly under varying electrical loads.
- Dimming or Loss of Backlight: A failing inverter may not be able to provide the necessary power to the display’s backlighting, causing it to dim or go completely dark.
- Unusual Noise: Some inverters produce a high-pitched whine when they are beginning to fail.
The technician will use a Digital Multimeter (DMM) to check the inverter’s input and output voltage. More importantly, an oscilloscope is used to examine the waveform of the inverter’s output. A clean, stable sine wave is expected. A noisy, distorted, or fluctuating waveform is a strong indication of an internal inverter failure.
The Servicing Process
Inverter servicing is not a matter of a simple repair. Modern avionics inverters are often sealed units that are not field-serviceable. The principle of authority dictates that the only approved method is to replace the inverter with a new or factory-repaired unit.
- Removal and Replacement: The technician will carefully disconnect the power and ground connections to the inverter, and remove the unit from its mounting location. A new or remanufactured inverter of the same make and model is then installed.
- Wiring and Connection Inspection: Before installing the new unit, the technician will inspect all wiring and connections for signs of corrosion, chafing, or loose terminals. A clean, secure connection is vital for the proper functioning of the inverter.
- Post-Installation Testing: After the new inverter is installed, the technician will perform a series of tests to verify its operation. This includes checking the voltage and waveform with the oscilloscope and performing an operational check on the glass cockpit display to ensure the flickering or dimming issue is resolved.
The Aero Center’s Commitment
At The Aero Center, we understand that a faulty power inverter can ground your aircraft. Serving California, Arizona, and Nevada, our certified technicians have the specialized tools and manufacturer-specific knowledge to diagnose and replace power inverters. We are the only 24/7 maintenance center in the area, a commitment that allows us to begin servicing your aircraft immediately, significantly reducing your downtime.
Footnotes
- AviationPros, “Troubleshooting Electrical Systems,” AviationPros, 2017. https://www.aviationpros.com/aircraft-maintenance-technology/article/12294452/top-tips-for-electrical-system-troubleshooting
- AOPA, “Avionics Upgrades and Maintenance,” Aircraft Owners and Pilots Association, 2024. https://www.aopa.org/go-fly/aircraft-and-ownership/avionics
- Lycoming, “Lycoming Engine Maintenance Manual,” Lycoming, 2024.
- Duncan Aviation, “Avionics Repair and Overhaul Services,” Duncan Aviation, 2024. https://www.duncanaviation.aero/services/avionics-components
The Aero Center is located at William J. Fox Airfield KWJF | Lancaster, CA. Contact us at 209.885.6950 for questions or appointments.