AV-20 ball not centered

[Rick Junkin]

The ball on my AV-20 is a bit more than half a ball to the left when my G5 and G3X balls are centered. The AV-20 is installed aligned with the other units.

Has anyone seen this?

Next step is a call to uAvionix.

Cheers,
Rick

[ArtVandelay]

When you power up, you should see a message about it aligning, do you see this? Is the plane stationary and level?

[Rick Junkin]

40 minutes ago, ArtVandelay said:

When you power up, you should see a message about it aligning, do you see this? Is the plane stationary and level?

Yes, the airplane is stationary and level at power on and the AV-20, G3X and G5 all go through their power-up alignment. The G3X and G5 align with a centered ball, and the AV-20 aligns with the ball out to the left. All three AIs align properly in pitch and wings level.

The AV-20 ball position is the only anomaly.

Cheers,
Rick

[PT20J]

I had the same problem. I called support and was told that the only way to center it was to physically rotate the instrument case. Mine was only about 1/8 ball off center. I drilled the mounting holes in the panel a little larger so I could rotate the instrument until the ball centered.

If it is mounted level and it’s that far off, I’d see if you can get a on warranty replacement because it sounds like it’s not right. 

Skip

[Rick Junkin]

12 minutes ago, PT20J said:

If it is mounted level and it’s that far off, I’d see if you can get a on warranty replacement because it sounds like it’s not right.

Thanks Skip, I’ll get some pictures to illustrate my situation and then contact uAvionix. 

Cheers,
Rick

[philiplane]

The plane must be leveled on jacks to get a proper calibration of all the instruments at the same time. You also need to know the panel tilt, it may not be what you think. With the plane leveled, the panel tilt is measured with a digital level, and that info gets programmed into the instruments. I've had many panels that are supposed to be zero tilt, or 8 degrees tilt, and then when measured accurately, they turn out much differently. A few had burrs on the backside of the mounting hole that threw the unit off by 2-3 degrees. The MEMS sensors in these units are tiny, and tiny errors in the mounting are magnified in use. The odds are that the problem lies in the installation and configuration, because uAvionix is making hundreds of these units to the same specs with the same parts. I've been involved in correcting dozens of problems like this with all the manufacturer's products, and I've yet to encounter an actual faulty unit. All were installation errors. 

Edited December 2, 2023 by philiplane

[Rick Junkin]

32 minutes ago, philiplane said:

I've been involved in correcting dozens of problems like this with all the manufacturer's products

What has been your experience with the AV-20 in particular? Is there a configuration method for the AV-20 beyond what's in the manual?

Cheers,
Rick

[philiplane]

I was an early AV20s adopter, before uAvionix bought them. Mine has been perfect. But i did physically align it, and my standby attitude indicator, and my Aspen PFD very carefully in the panel. All three are perfectly level to the spar, and perfectly square to the panel. Which is not truly vertical, it has a 2.5 degree tilt. If the unit is off a few degrees in roll, it will also be off in yaw. So make sure it really is level in roll and agrees with the other attitude indicators.

Doing the hard calibration while the plane is perfectly level in pitch and roll will show if the unit really is out of spec.

And don't take the Garmin units info as gospel. Installers can goof them up too. They have software based pitch and roll offsets to account for discrepancies in the physical mounting, and those can be incorrect. This is all too common of a problem.

To be clear, this calibration applies to the AV-20-S, not the plain AV-20.

Edited December 2, 2023 by philiplane

[0TreeLemur]

I've owned two AV-20-S's.  Both centered just fine.

[PT20J]

It’s easy to level the airplane laterally without jacks. The reference is the seat rails. Place a level across the left and right rails nearest the longitudinal centerline. If it is not level, let the air out of one main tire until it levels. But, with both tires inflated equally, it should sit very close to level if the ground is level.

Panel tilt shouldn’t affect the ball centering: My M20J sits 5 deg ANU (aircraft nose up) on the ground with the ball centered in the hangar, climbs at 7 deg ANU with the ball centered, descends 3 deg AND with the ball centered and cruises level with the ball centered. 

The G3X, G5 and AV-20-S were all initially calibrated with the aircraft leveled on jacks. When the ball on the AV-20-S didn’t exactly center, we tried recalibrating with the airplane sitting on the wheels. Made no difference. That’s when we called support and found that the calibration doesn’t center the ball.

[thinwing]

my av 20 is mounted in a gyro copter and both attitude and slip are off..ie the attitude line is 15 degrees or so diving into the brown (earth)and slip ball is a full ball width displaced to the right.The manual states pressing both lower buttons while in attitude display ..ie psync should zero the display.but does nothing.The panel is tilted downward but I can find noplace in manual to program in that tilt.Uvionix says send unit back for warrenty.

[PT20J]

33 minutes ago, thinwing said:

psync should zero the display.but does nothing

Sounds defective. Mine zeros out in pitch.