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  #1  
Old 08-23-2023, 07:49 AM
Amadeus's Avatar
Amadeus Amadeus is offline
 
Join Date: Nov 2020
Location: Basalt, CO/Lexington, KY
Posts: 284
Default "NO ALT" Message

My panel is the -12iS dual G3X package with a GPS175 navigator added. Recently, the last 5 or 6 flights, a "NO ALT" message appears occasionally over the transponder code. "NO ALT" is never on for more than 10 seconds at a time and "XPDR" is displayed the rest of the time.

I did pull a PAPR and in the Exceptions the NIC box was red.

Missing Elements has BAlt red with 3.51% fail, Max dT 0:00:11 and MCF 11

Integrity & Accuracy has the NIC box red with 16.92% fail, Max dT 0:00:23, MCF 26, AVG 7.4, Min 0 and Max 9

Are these acceptable error levels?
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RV-12iS
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  #2  
Old 08-23-2023, 08:07 AM
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rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: Winfield Park, NJ
Posts: 489
Default

You should be seeing 0% failures.

The xpdr is getting intermittent barometric data from the G3X.. In the stock configuration, the xpdr gets its ADSB-compliant GPS data over its Serial 3 port from the GPS 20A unit... which you may have rewired now that you have the GPS175 in the mix..

The xpdr also gets ADAHARS data from the GSU25 over its Serial 1 port (pins 9 & 31 at the xpdr and pings 9&10 at the ADAHARS unit under the baggage floor). The xpdr broadcasts your pressure altitude and heading.. and it gets that info directly from the GSU25.

Assuming the G3X is showing good data all the time and no error messages, I'm thinking something is up with that serial line.. intermittent connection, something grounding out etc.

I've attached a report from my plane for a 1 hour flight for your reference. This was at normal altitudes and within normal radar coverage areas in my area.
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RV-12iS (N713) / Completed 12/2020 / 510hrs and counting
ASEL, Glider, AGI/IGI, LSRM-I, FCC GROL
APRS Track or ADSBExchange Track

Last edited by rcarsey : 08-23-2023 at 08:40 AM.
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  #3  
Old 08-23-2023, 08:09 AM
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g3xpert g3xpert is offline
 
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Location: Olathe, KS
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Default PAPR

Quote:
Originally Posted by Amadeus View Post
My panel is the -12iS dual G3X package with a GPS175 navigator added. Recently, the last 5 or 6 flights, a "NO ALT" message appears occasionally over the transponder code. "NO ALT" is never on for more than 10 seconds at a time and "XPDR" is displayed the rest of the time.

I did pull a PAPR and in the Exceptions the NIC box was red.

Missing Elements has BAlt red with 3.51% fail, Max dT 0:00:11 and MCF 11

Integrity & Accuracy has the NIC box red with 16.92% fail, Max dT 0:00:23, MCF 26, AVG 7.4, Min 0 and Max 9

Are these acceptable error levels?
Jayson,

Can you please email us a copy of the complete PAPR report to G3Xpert@Garmin.com?

Thanks,

Justin
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  #4  
Old 08-23-2023, 09:23 AM
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Amadeus Amadeus is offline
 
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Location: Basalt, CO/Lexington, KY
Posts: 284
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Quote:
Originally Posted by g3xpert View Post
Can you please email us a copy of the complete PAPR report to G3Xpert@Garmin.com?
Yes; just sent.
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Jayson
RV-12iS
E-LSA

“Never feel sorry for a man who owns a plane.” -Charles Morse (Anthony Hopkins) Movie - "The Edge" https://youtu.be/dJD0lB4zRes
"...except during the month of Annual Condition Inspection." -Me (in the hangar)
"My first wife didn't like airplanes." - Gordon Baxter
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  #5  
Old 08-31-2023, 10:14 AM
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Amadeus Amadeus is offline
 
Join Date: Nov 2020
Location: Basalt, CO/Lexington, KY
Posts: 284
Default

Garmin g3xpert is reviewing flight log data in comparison to the PAPR.

No update as yet.
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Jayson
RV-12iS
E-LSA

“Never feel sorry for a man who owns a plane.” -Charles Morse (Anthony Hopkins) Movie - "The Edge" https://youtu.be/dJD0lB4zRes
"...except during the month of Annual Condition Inspection." -Me (in the hangar)
"My first wife didn't like airplanes." - Gordon Baxter

Last edited by Amadeus : 08-31-2023 at 10:20 AM.
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  #6  
Old 08-31-2023, 10:23 AM
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mburch mburch is offline
 
Join Date: Feb 2005
Location: Oregon
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Quote:
Originally Posted by rcarsey View Post
Assuming the G3X is showing good data all the time and no error messages, I'm thinking something is up with that serial line.. intermittent connection, something grounding out etc.
Yes, this is the right approach. Be sure to verify both of the RS-232 conductors between the GSU 25 and transponder (transmit and receive) are connected and working; I have seen this same behavior when the RX pin on the GSU 25 is not connected.
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Last edited by mburch : 08-31-2023 at 10:32 AM.
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