My RV-10 has a G3X (non touch) panel with a GTN-650 as the TSO'd navigator for IFR flight, of which I do a lot. The whole shebang has been working great for +400hrs (including 2 Atlantic crossings) without so much as a hiccup. That is until recently when I installed the latest software update for both the G3X (12.20) and the GTN (6.71). All worked fine on a 20min test flight as well as on the first (40min VFR) leg of a long XC about a week later. On the 2nd leg, about 30 min into a 2hr IFR flight, the GTN turned itself off and rebooted. It continued to turn off and reboot like this for the remainder of the flight. Same for the 3rd 2hr leg back home. Put the plane away and went back to the hangar the next day to troubleshoot. Turned on the panel and the GTN boots up, then the screen goes black with a white vertical line down the middle...
A call to Garmin and they say the unit needs to be returned for service. I pony up the $1,500 or so and receive a refurb unit in short order. Slide the new unit in and it comes to life as expected. I check the software version and it's up-to-date with ver 6.71. Expecting my troubles to be over, I head out for a test flight and guess what - it reboots again...
By now I'm thinking I must have an intermittent power supply or ground issue, so I bring up the VPX Pro page on the G3X and wait for it to happen again. There it goes, but there's no fault message on the VPX, no open, no short, no over current - nothing. In fact, the breaker shows a steady 2.9 Amps throughout, even with the screen dark...
Hmm... Time for a deeper dive. I have the GTN wired through a couple of Shottky diodes as part of a dual bus system, so I disconnect the Aux power and connect the GTN power directly to the main avionics power to bypass the diodes altogether. No dice, still shuts off in flight - it's not a bum diode.
Deeper still - I have 2 (electronic) breakers feeding the GTN, one for the COM radio (connector P1003) along with my Audio Panel, and one for the Main board (connector P1001, the VHF NAV board (connector P1004) and my Airinc module, a GAD 29.
I try turning off the breakers in flight - the COM breaker kills the Audio Panel and delivers the appropriate warning on the GTN that the radio is inop, although the screen is still up and the rest of it seems to be working normally.
Pulling the NAV breaker turns the GTN off completely as expected, since the main board is turned off when pins 19 and 20 are depowered in connector P1001. I'm starting to run out of ideas for an easy fix, so I bust out the multimeter and tear into the panel looking for a bad crimp, loose connector or some other builder induced failure (I built the panel...).
I'm in deep now, screens out, avionics racks out, connectors disassembled and every one of those pesky high density pins Ohmed out, wiggled, pulled and thoroughly checked out. Nothing... I put it all back together.
Getting just a little defeated by now... One last feeble idea before I go back to Garmin and plead for help... I hook up the audio panel to the same breaker as the Main GTN board in the hopes that if there is an intermittent power interruption, maybe I'll hear a click in the system to give me a clue.
Last test flight and I wait for the inevitable reboot. The GTN turns off after 20min or so and reboots. Not a click, a flicker or a peep from anything else in the panel. The Audio Panel seems to be doing just fine. I'm exhausted.
Call up Garmin on Tues morning and talk to a member of Team X. I get a couple of sentences out and he stops me, says he's heard of something like this and will get with one of the engineers and call me back. Cool, maybe I'm gonna get this fixed! No call by 4pm, so I call again and get the same guy that helped me with the exchange unit a few weeks earlier. He seems genuinely interested in helping and says he's never heard of anything like this. I go through all my troubleshooting and ask if it could possibly be software related, since it has happened on 2 units now with ver 6.71. He says there are so many units in operation with the new software and nobody else has had a problem. Nevertheless, he takes my info again and promises a follow-up email to gather more info for the engineers. Saturday now and nothing in my inbox.
Any ideas from the collective on this one?
A call to Garmin and they say the unit needs to be returned for service. I pony up the $1,500 or so and receive a refurb unit in short order. Slide the new unit in and it comes to life as expected. I check the software version and it's up-to-date with ver 6.71. Expecting my troubles to be over, I head out for a test flight and guess what - it reboots again...
By now I'm thinking I must have an intermittent power supply or ground issue, so I bring up the VPX Pro page on the G3X and wait for it to happen again. There it goes, but there's no fault message on the VPX, no open, no short, no over current - nothing. In fact, the breaker shows a steady 2.9 Amps throughout, even with the screen dark...
Hmm... Time for a deeper dive. I have the GTN wired through a couple of Shottky diodes as part of a dual bus system, so I disconnect the Aux power and connect the GTN power directly to the main avionics power to bypass the diodes altogether. No dice, still shuts off in flight - it's not a bum diode.
Deeper still - I have 2 (electronic) breakers feeding the GTN, one for the COM radio (connector P1003) along with my Audio Panel, and one for the Main board (connector P1001, the VHF NAV board (connector P1004) and my Airinc module, a GAD 29.
I try turning off the breakers in flight - the COM breaker kills the Audio Panel and delivers the appropriate warning on the GTN that the radio is inop, although the screen is still up and the rest of it seems to be working normally.
Pulling the NAV breaker turns the GTN off completely as expected, since the main board is turned off when pins 19 and 20 are depowered in connector P1001. I'm starting to run out of ideas for an easy fix, so I bust out the multimeter and tear into the panel looking for a bad crimp, loose connector or some other builder induced failure (I built the panel...).
I'm in deep now, screens out, avionics racks out, connectors disassembled and every one of those pesky high density pins Ohmed out, wiggled, pulled and thoroughly checked out. Nothing... I put it all back together.
Getting just a little defeated by now... One last feeble idea before I go back to Garmin and plead for help... I hook up the audio panel to the same breaker as the Main GTN board in the hopes that if there is an intermittent power interruption, maybe I'll hear a click in the system to give me a clue.
Last test flight and I wait for the inevitable reboot. The GTN turns off after 20min or so and reboots. Not a click, a flicker or a peep from anything else in the panel. The Audio Panel seems to be doing just fine. I'm exhausted.
Call up Garmin on Tues morning and talk to a member of Team X. I get a couple of sentences out and he stops me, says he's heard of something like this and will get with one of the engineers and call me back. Cool, maybe I'm gonna get this fixed! No call by 4pm, so I call again and get the same guy that helped me with the exchange unit a few weeks earlier. He seems genuinely interested in helping and says he's never heard of anything like this. I go through all my troubleshooting and ask if it could possibly be software related, since it has happened on 2 units now with ver 6.71. He says there are so many units in operation with the new software and nobody else has had a problem. Nevertheless, he takes my info again and promises a follow-up email to gather more info for the engineers. Saturday now and nothing in my inbox.
Any ideas from the collective on this one?
Last edited: