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GTX345 Been our of the Air Too Long?


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F999A0D9-5F6B-430D-976B-12CE83BA75C1.jpeg

 

I was sick and the Mooney was on the ground since February 13th.  I flew it about 45 minutes this morning, landed then flew about 45 minutes home.  In ForeFlight More/Devices it showed connected to the transponder, but it didn’t show anything at all in the upper left corner of the chart to indicate ADS-B Good or anything like I have seen before.

 

After seeing the messages above I looked them up in the GTX 345 Pilot Guide.  In the troubleshooting chart common between all three messages is a possible problem worded as follows:   “Extended periods between use or GPS position source disconnection from the aircraft battery could cause a longer than normal GPS acquisition time

anyone ever seen this?

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1 hour ago, MBDiagMan said:

F999A0D9-5F6B-430D-976B-12CE83BA75C1.jpeg

 

I was sick and the Mooney was on the ground since February 13th.  I flew it about 45 minutes this morning, landed then flew about 45 minutes home.  In ForeFlight More/Devices it showed connected to the transponder, but it didn’t show anything at all in the upper left corner of the chart to indicate ADS-B Good or anything like I have seen before.

 

After seeing the messages above I looked them up in the GTX 345 Pilot Guide.  In the troubleshooting chart common between all three messages is a possible problem worded as follows:   “Extended periods between use or GPS position source disconnection from the aircraft battery could cause a longer than normal GPS acquisition time

anyone ever seen this?

A longer than normal time shouldn't be 90 minutes of flying. I remember the original Garmins from the early 1990s would take forever to locate you if the unit was turned on. "Forever" was never more than 15 minutes. If you have the 345 without the onboard GPS, the GPS is coming over from the GNS or GTN. Did you have any issues with it?

 

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The GPS constellation is in a continuous state of flux.  In order to aid in acquisition time, modern gps units maintain an “almanac” of ephemeris data... basically the coarse positions of all the satellites.  As you use your GPS, this data is also downloaded into the receiver and updated.  

If you haven’t used your GPS in a while, it’s almanac will be out of date, and it won’t be able to compute your position without re-downloading the entire almanac first.  The almanac is re-broadcast every 12.5 minutes... thus...it shouldn’t take more than 25 minutes to re-load the almanac.

 My guess on your issue: either your antenna has failed, the wiring between the antenna and the unit has failed, or the unit itself has failed.  If you had a clear view of the sky, though, and flew for 90 minutes... then you most certainly gave the system enough time to download a new almanac.

oh, if GPS was being jammed in your area- you also wouldn’t get an almanac... but that should have been NOTAM’d.

 

Edited by M016576
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Thanks guys!  I think I have it figured out, but I am too embarassed to explain.  Once I confirm that what I found is indeed the issue I will explain.  I am most definitely in learning mode.


Just remember, when it comes to avionics, there is no such thing as a stupid pilot, only pilots who didn’t read the manual.


Sent from my iPad using Tapatalk Pro
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1 hour ago, MBDiagMan said:

Thanks guys!  I think I have it figured out, but I am too embarassed to explain.  Once I confirm that what I found is indeed the issue I will explain.  I am most definitely in learning mode.

Let me guess you were trying it inside of the hangar?

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No, the problem that I didn’t have traffic selected in Fore flight.  I discovered that when I went up in the Cessna for a few trips around the patch.  It has a newly installed Stratus ESG, so I was thinking how could both transponders be having problems?  There may have been traffic on the 430, but I wasn’t watching it for traffic.  I was watching Foreflight.  My card compass bracket broke when I got home.  I ordered a mount, but I won’t be flying the Mooney until it gets here.  The compass is hanging by the light wires.  I am getting tailwheel time until then.

Anyway I was outside between rows of hangars when I took the picture above and the plane had set there awhile after I landed before I had found the message and took the pictures.

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6 hours ago, MBDiagMan said:

No, the problem that I didn’t have traffic selected in Fore flight.  I discovered that when I went up in the Cessna for a few trips around the patch.  It has a newly installed Stratus ESG, so I was thinking how could both transponders be having problems?  There may have been traffic on the 430, but I wasn’t watching it for traffic.  I was watching Foreflight.  My card compass bracket broke when I got home.  I ordered a mount, but I won’t be flying the Mooney until it gets here.  The compass is hanging by the light wires.  I am getting tailwheel time until then.

Anyway I was outside between rows of hangars when I took the picture above and the plane had set there awhile after I landed before I had found the message and took the pictures.

Not sure I understand you right, FF not having traffic selected shouldn’t cause those messages on the transponder at all.  Transponder doesn’t care how you have FF set up, the messages are internal to the transponder.

 I’m definitely curious about this as well since I also have a GTX345.

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I wasn’t clear.  The reason I saw no traffic on FF turned out to be that I had Traffic turned off.  Once on the ground after the flight I discovered the messages.  The messages either were set at the beginning of the flight because it had sat so long or at the end when powering up the transponder to investigate.

Sorry

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