[uk_figs]

For those with a 175/375 in a tailwheel aircraft how did you calibrate the AHRS system. I tried it with the aircraft level (leveled in pitch and roll via the slider rails) and it gave weird results in the synthetic vision mode on the 760 and on Foreflight on the iPad. I also tried the "cage gyros" mode in smooth air level flight but that did not seem to set a persistent pitch and roll offset.
I am also not sure if the cage gyros mode actually adjusts the AHRS configuration settings or just sets a pitch and roll offset (same question for Foreflight on the iPad).

I just recalibrated with the -7 sitting in the normal ground position and the synthetic vision seemed to be somewhat correlated (showed level wings and about 9 deg pitch up).

Any input appreciated.
Thanks
Figs

 

[uk_figs]

AHRS Re calibration

Planning to recalibrate the GNX AHRS this weekend, anyone know offhand if the side cockpit rails on a -7 slider are at 0 deg pitch in normal level flight?
Figs

 

[uk_figs]

AHRS Calibration

Still having trouble with the GNX375 AHRS calibration and maybe the G3Expert can provide some insight.
I found some AHRS calibration instructions for the G5 and it said to calibrate in level flight mode so yesterday I put the -7 in a zero pitch and roll position (used the slider rails for pitch and roll angle setup). I ran the calibration process and at the end when it said the process was successfully completed it showed -8 deg pitch and -1 deg roll? The display on the Aera 760 and the iPad however showed about a 15 deg bank and a few degrees pitch down.

I then zero'd pitch and roll on the Foreflight synthetic visuion display and the aera 760 also showed level flight so obviously the iPad talked to the 375 which then talked to the 760 (all connected via BT)

I then flew a test flight and the synthetic vision displays on the 760 and Foreflight were not correct in level flight, showing a bank and pitch attitude.

The AHRS information is sent over the Connext BT link.

I am confused about the -8 deg pitch calibration unless that is the angular difference between the standard Van's panel and the longerons which would impact the horizontal angle of the 375 tray. But still cannot explain why the synthetic vision display would be so far off.

G3Expert any ideas?
Figs

 

[Dan 57]

G3Expert will probably jump in, but in the meantime you got me confused

My -6.9i sports a dual G5/GNX375 config. Now AFAIK the 375 has nothing directly to do with the AHRS, since the AHRS itself is installed in either a G5, or a G3X as I suspect you are using. OTH I learned that a valid GPS signal is necessary for augmented stabilization, and this is acquired thru the 375 since the internal G5 GPS signal is frequently blocked off.

When I did my AHRS calibration I set the tail wheel on a trestle so the cockpit rails were level. Subsequent inflight testing showed a need for pitch offset of about 3°, so I assume the tail should have been lifted another few degrees to approach inflight pitch. That being said, inflight pitch is also function of the speed one flies at…

Not sure this helps any, but good luck.

 

[Richard Connell]

Still having trouble with the GNX375 AHRS calibration and maybe the G3Expert can provide some insight.
I found some AHRS calibration instructions for the G5 and it said to calibrate in level flight mode so yesterday I put the -7 in a zero pitch and roll position (used the slider rails for pitch and roll angle setup). I ran the calibration process and at the end when it said the process was successfully completed it showed -8 deg pitch and -1 deg roll? The display on the Aera 760 and the iPad however showed about a 15 deg bank and a few degrees pitch down.

I then zero'd pitch and roll on the Foreflight synthetic visuion display and the aera 760 also showed level flight so obviously the iPad talked to the 375 which then talked to the 760 (all connected via BT)

I then flew a test flight and the synthetic vision displays on the 760 and Foreflight were not correct in level flight, showing a bank and pitch attitude.

The AHRS information is sent over the Connext BT link.

I am confused about the -8 deg pitch calibration unless that is the angular difference between the standard Van's panel and the longerons which would impact the horizontal angle of the 375 tray. But still cannot explain why the synthetic vision display would be so far off.

G3Expert any ideas?
Figs

I don't have a 375 in a 7 but I have had an RV7 and I have a GNC355 (which I assume in respect of the internal AHRS is identical to a 175/375) in the RV10 which has both a pitch and yaw adjustment relative to the longeron/level flight attitude.
The RV7 panel is tilted forward 8 degrees from level flight - but I don't believe you need to tell the GNX375 this when you perform the AHRS cal. Only if you have a yaw offset which I imagine is rare (I have my radio stack canted towards the pilot).
The cal procedure is the same as the GSU25/GMC507/G5. level to flight attitude in pitch and roll. Do them all at the same time for convenience. Im 99% sure the 175/355/375 AHRS is not involved in any miscompare monitoring so you can do it separately if you like. The others should be done together.

Im not 100% how the Attitude solution over BT works with the Ipad and the Aera, but I had my copilot fiddling with it a few flights ago trying to get the AHRS onto FF. It appeared that it was more of a "relative" attitude augmentation and that he had to reset the attitude periodically. This sounds similar to the issue you have. It wasn't great tbh - looked a little bit gimmicky. Maybe its seamless with Garmin Pilot. not sure.
Caveat, I haven't read the manual for sending AHRS over BT to FF on an Ipad. But my CP is a smart technical guy and if he can't get it working easily its of zero use as a backup IMHO. If you could get it stable it should be handy for a copilot or back seater though.

 

[uk_figs]

I don't have a 375 in a 7 but I have had an RV7 and I have a GNC355 (which I assume in respect of the internal AHRS is identical to a 175/375) in the RV10 which has both a pitch and yaw adjustment relative to the longeron/level flight attitude.
The RV7 panel is tilted forward 8 degrees from level flight - but I don't believe you need to tell the GNX375 this when you perform the AHRS cal. Only if you have a yaw offset which I imagine is rare (I have my radio stack canted towards the pilot).
The cal procedure is the same as the GSU25/GMC507/G5. level to flight attitude in pitch and roll. Do them all at the same time for convenience. Im 99% sure the 175/355/375 AHRS is not involved in any miscompare monitoring so you can do it separately if you like. The others should be done together.

Im not 100% how the Attitude solution over BT works with the Ipad and the Aera, but I had my copilot fiddling with it a few flights ago trying to get the AHRS onto FF. It appeared that it was more of a "relative" attitude augmentation and that he had to reset the attitude periodically. This sounds similar to the issue you have. It wasn't great tbh - looked a little bit gimmicky. Maybe its seamless with Garmin Pilot. not sure.
Caveat, I haven't read the manual for sending AHRS over BT to FF on an Ipad. But my CP is a smart technical guy and if he can't get it working easily its of zero use as a backup IMHO. If you could get it stable it should be handy for a copilot or back seater though.

Thanks for the info, the 8 degree panel angle make the calibration numbers now make sense. I now have to figure out the BT/Connext piece as to why after the calibration the portable devices did not show level. I do not see any adjustments other than the "zero pitch and roll" and "cage gyros" on foreflight and the aera 760 respectively. The 760 has an internal AHRS but the only calibration seems to be the "cage gyros" function when the aircraft is in level attitude.
Figs