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alcladrv

Well Known Member
I keep a United altimeter operational alongside my G3X. During my biennial pitot/static and transponder check today, the tech said that the United altimeter was dead on (well within the 20 ft. tolerance). He said the FARs didn't allow him to just certify the United altimeter and use the G3X as reference. All altimeters in the plane had to be certified and within limits.

He said the G3X was right at the limit and it was a coin flip whether he'd certify it or not. So he certified it and mentioned that there might be an offset in the configuration settings. Does such an offset capability exist (other that adjusting the BARO setting) and, if so, how do I access it?

Thanks,

Mike
 
Just had mine done and the tech was amazed at how accurate the G3X was.

Saw a similar thread here a few days ago.

I am not aware of any offset the end user can get to. Steve will most likely be along to shed some light on this.

You may have to send it to them to be re-calibrated.

The 20ft tolerance is only required at the very low end of the range:

2h49b4h.png


Are you sure he set the baro to 29.92 before doing the test?
 
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alcladrv said:
I keep a United altimeter operational alongside my G3X. During my biennial pitot/static and transponder check today, the tech said that the United altimeter was dead on (well within the 20 ft. tolerance). He said the FARs didn't allow him to just certify the United altimeter and use the G3X as reference. All altimeters in the plane had to be certified and within limits.

He said the G3X was right at the limit and it was a coin flip whether he'd certify it or not. So he certified it and mentioned that there might be an offset in the configuration settings. Does such an offset capability exist (other that adjusting the BARO setting) and, if so, how do I access it?

Thanks,

Mike
Click to expand...

Hello Mike,

The G3X system does not support a simple "offset" as we have never had confidence that any needed correction could be addressed by a simple offset of the entire altimeter calibration curve.

It has been very rare for an altitude sensor in a GSU73 to drift enough to require re-calibration to pass this testing, but when needed, Garmin and our dealers have access to a PC tool that communicates with the GSU73 over USB or RS-232 and can re-calibrate the unit to correct this error.

This question is somewhat timely because we are working on a project now to move this re-calibration capability out of the PC tool and into the GDU 37X and GDU 46X displays so you can perform this re-calibration in the plane when needed.

Please call or email us if you wish to discuss further, but by the time your pitot/static test comes around again, you should be able to use a configuration screen on the display in combination with the test set to re-calibrate the altimeter across the entire range of operation.

Thanks,
Steve
 
Steve,

Thanks for your response.

In nearly 3 years of operating the G3X, the altitude difference with the United altimeter hasn't changed. This is the first time I've had the G3X certified. Until recently, I didn't have an autopilot with altitude hold so I just adjusted the BARO on the G3X so the altitude matched the United altimeter.

I'll be keeping the United altimeter as a rock solid backup in case the lights go out on the G3X.

The tech is a Garmin dealer typically installing G300 and G600 systems. I'll look forward to the configuration setting updates.

Mike
 
g3xpert said:
Hello Mike,


This question is somewhat timely because we are working on a project now to move this re-calibration capability out of the PC tool and into the GDU 37X and GDU 46X displays so you can perform this re-calibration in the plane when needed.

Please call or email us if you wish to discuss further, but by the time your pitot/static test comes around again, you should be able to use a configuration screen on the display in combination with the test set to re-calibrate the altimeter across the entire range of operation.

Thanks,
Steve
Click to expand...

Steve,
I Will be going through the testing/calibration process on my new G3X/dual ADAHRS panel upgrade in the next few weeks if you need someone in the field to work with. My P-S test box is RVSM certified.
Walt
Walt
 
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