Lost com G1000

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csalewski
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Lost com G1000

Post by csalewski »

On Sunday I took off at KLZU and on the roll heard a faint popping sound in my headset.
Made my call to request frequency change shortly after but I had no audio either on COM 1 with the tower frequency nor on COM 2 with the ATIS dialed in. Ok, my first lost com.

In-flight tests:
- RX and TX indication on the G1000 was shown
- No audio feedback when talking
- Headset was plugged in correctly
- All circuit breakers in
- I tried co-pilot plugs
- I tried a 2nd headset
- No audio on the speaker
- Bose headset turned off after a few minutes indicating that there was no power on the plug

Set up to land at next uncontrolled airport KGVL which was on my way (as soon as practicable) and used my handheld radio. Confirmed with FBO that I was not transmitting on COM1. They just heard a click but no voice.
-> Oddly enough on downwind I heard a humming sound and my radios were back - 25 minutes into the flight.

Anybody had this happened before with a G1000 equipped DA40-180? Any ideas?
Is the GMA1347 audio panel doing the amplification and providing power to the plugs or is there anything in between?

Max Trescott writes in his "G1000 glass cockpit handbook" in chapter 5 that "if the audio panel ever fails in flight, the G1000 will bypass the audio panel and connect (...) directly to COM 1 audio."
I'll have to verify that with the Garmin literature. So maybe not the audio panel?
And since it's working now it will be hard to trouble shoot. Going to the avionics shop tomorrow.

Carsten
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Re: Lost com G1000

Post by acyr »

I had a failed GMA1347 a few months ago and radio defaulted to com1.
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Re: Lost com G1000

Post by Jean »

Happened to me once because the volume button was set to zero on the PFD !
Took me a few minutes to find out what was going on.
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csalewski
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Re: Lost com G1000

Post by csalewski »

I taxied to the shop today - no radio.
But they were not able to reproduce it later. They visually checked all accessible wiring w/o any findings.
Next step is to measure all connections assuming an intermittent short circuit somewhere between the audio panel and the plugs.
acyr wrote:I had a failed GMA1347 a few months ago and radio defaulted to com1.
My GMA1347 did not default to COM1 but it could still be the source of the problem.
Did you have to exchange it? How much?

Carsten
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Re: Lost com G1000

Post by acyr »

The exhange was something like $800, mine actualy did give a message on the pfd that it had failed.
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Re: Lost com G1000

Post by Star57 »

csalewski wrote:I taxied to the shop today - no radio.
But they were not able to reproduce it later. They visually checked all accessible wiring w/o any findings.
Next step is to measure all connections assuming an intermittent short circuit somewhere between the audio panel and the plugs.
acyr wrote:I had a failed GMA1347 a few months ago and radio defaulted to com1.
My GMA1347 did not default to COM1 but it could still be the source of the problem.
Did you have to exchange it? How much?

Carsten
Just had the same problem today with my Audio Panel, out of no where, the Audio died, we were in the process of doing the run up, reset the breakers for Com 1 and Com 2 nothing, reset the Avionics switch and it came back, by then we had already come back to the Hangar, this is the second time that it happened, so its an intermittent complete failure on the Audio Panel, my buddy thinks it may be some loose connection to or from the Avionics switch to the Audio Panel, he suggested using some electronic contact cleaner, if that doesn't do it, we need to exchange the Audio Panel and possibly the Avionics switch.

Anyone has any other ideas?
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Re: Lost com G1000

Post by Rick »

Star57 wrote:Just had the same problem today with my Audio Panel, out of no where, the Audio died, we were in the process of doing the run up, reset the breakers for Com 1 and Com 2 nothing, reset the Avionics switch and it came back, by then we had already come back to the Hangar, this is the second time that it happened, so its an intermittent complete failure on the Audio Panel, my buddy thinks it may be some loose connection to or from the Avionics switch to the Audio Panel, he suggested using some electronic contact cleaner, if that doesn't do it, we need to exchange the Audio Panel and possibly the Avionics switch.

Anyone has any other ideas?
The avionics switch controls more than just the audio panel - did you notice if COM2 and NAV2 were on or not? How about your autopilot? If any of those things were on but no audio panel, then it's not the Avionics switch. If ALL of that stuff was off, but then on, it probably IS the switch.
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Re: Lost com G1000

Post by Star57 »

Rick wrote:
Star57 wrote:Just had the same problem today with my Audio Panel, out of no where, the Audio died, we were in the process of doing the run up, reset the breakers for Com 1 and Com 2 nothing, reset the Avionics switch and it came back, by then we had already come back to the Hangar, this is the second time that it happened, so its an intermittent complete failure on the Audio Panel, my buddy thinks it may be some loose connection to or from the Avionics switch to the Audio Panel, he suggested using some electronic contact cleaner, if that doesn't do it, we need to exchange the Audio Panel and possibly the Avionics switch.

Anyone has any other ideas?
The avionics switch controls more than just the audio panel - did you notice if COM2 and NAV2 were on or not? How about your autopilot? If any of those things were on but no audio panel, then it's not the Avionics switch. If ALL of that stuff was off, but then on, it probably IS the switch.
Thanks for your input, the comms were alive but no transmission on either, the A/P was on, I'm going to try to clean all connections to the Audio Panel and see what happens...
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Re: Lost com G1000

Post by rwtucker »

Carsten, Did you try a quick R&R of the LRU? CFI Dave outlined the steps in DAN about six months ago. If that turns out to solve the problem, I would regard it as temporary and add some Stabilant 22 to the contacts when you get time. http://www.amazon.com/Stabilant-5ml-Kit ... bilant+22a Some of the DAN members report having good luck with it. Less likely, but you might also try R&R on the associated RF connectors.
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Re: Lost com G1000

Post by Steven M »

I lost all my COM shortly after buying my DA40 new in '06 while approaching a landing near Portland, OR just after ATC handed me off to the tower. Long story short - my hand held mike was located in the storage pocket and plugged in when I purchased the plane. I had stored some charts and other things in that pocket on top of the mike and they keyed the mike which prevented me from hearing anything the controllers were saying. In you have one of those mikes, unplug them unless needed.
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