Every new iteration of the SR series presents new opportunities for owners and maintenance providers to learn all the changes that aren’t in the sales brochures. The G7 is no exception with the really nice upgrade in the Garmin avionics suite. Changes were made with regard to the headset power that are just now coming to light.
One of our early G7 adopters reported that their headset batteries were not staying charged when plugged into the plane’s LEMO connectors. They could remove the headset battery packed and the noise cancelling feature would cease to function. It seemed like an obvious electrical power supply issue from the aircraft to the headset. Unfortunately, this was very early in G7’s availability, and all the new wiring diagrams were not readily available.
A few calls to Cirrus support revealed that there was a dedicated power source from the main bus to the headset power via an in-line fuse. All we needed to do was find this fuse, but Cirrus couldn’t tell us exactly where it was located. A little deduction and common sense suggested that an in-line fuse should be mounted close to its power source, so we began our search at the circuit breaker panel. It was a bit like the children’s books “Finding Waldo” except that Waldo didn’t look like we expected him to look. The typical in-line fuse holder is a couple of inches long and about a half inch in diameter. There wasn’t anything like that in the circuit breaker panel. The only thing that saved us was that we’d been told the fuse was identified as “FS2020”. Eventually, someone noticed a partial view of a label that might be “FS2020”, but it wasn’t mounted on the expected size fuse holder.
A couple of typical sized in line fuse holders can be seen which are labeled “F644” and “F646”. The little fuse holder labeled “FS2020” is in this photo but hiding almost out of view.
Once we started cutting zip ties and exposing the suspected fuse holder, we could see it was a miniature version of what we expected. In fact, the brand name is “Littelfuse”, and it lived up to it. Sure enough, the fuse was tested and found open. Not being a standard part of our inventory (it is now), we ordered a few of these fuses Cirrus part number 50961-004 for this repair and to have some on hand for the next time.
A closer view zoomed in to reveal a bit more of the “FS2020” label hiding under a bundle of wires
Just a size comparison for reference
Upon installation of the new fuse. we were prepared to find that it would burn open as well, but it didn’t. The headset returned to its normal operation, and all is well except that we don’t know what caused the fuse to blow in the first place. Not knowing the cause gnaws at me. For now, I’ll just believe the original fuse was defective from manufacturing.
If your G7 headsets give trouble with charging or not staying in noise cancelling mode, just go for a dive into the circuit breaker panel for the little fuse. It’s there, but it may be hiding.
Copyright © 2025 Paul New
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