TIL a bad ground can wreck a whole GPS nav system on some Cessnas

I read in an Avionics Today article last week that a single .5 ohm ground fault on a Garmin G1000 can cause it to lose signal completely during approach. Any of you ever chased a ghost like that and found it was just a dirty ring terminal?

2 comments

2 Comments

tyler6141mo ago

Used to think ground issues were overblown until I chased a intermittent radio dropout on a buddy's 172 for three weekends... turned out to be a corroded terminal under the panel that looked fine until you wiggled it. That .5 ohm number lines up with what I saw on the multimeter once we finally got the probe on the right spot. Definitely changed how I approach electrical troubleshooting now.

ivan821mo ago

Drove myself crazy for a WEEK on my own plane thinking the alternator was shot. Everything tested fine until I accidentally bumped the master switch panel and the lights flickered. Turned out the ground strap was basically a pile of green dust hidden under a cable bundle. Felt like a real genius when I finally found it. That .5 ohm number is the magic threshold for sure, once you see it you never forget it. Now I start EVERY electrical check with a good wiggle test and a prayer.