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GRT Sport EX: potential AHRS "anomalies"

Jvon811

Jvon811

Well Known Member
I'm hesitant to call it a problem yet...

I've gotten a lot of enjoyment out of my Sport EX and I do think it's a good product. Lots of capability in a small package at a good price. And the little problem I did have was met with EXCELLENT service. No complaints...

That all being said, I've been having some attitude indication problems during aerobatics. The device is supposedly good for it, I fly well within G limits and Roll Rate limits of the gyros. But I have been in touch with GRT and this "anomaly" is being looked into already. I've recorded this video and sent it to GRT along with a log file so they can chase it down and figure out why my attitude indications aren't behaving like they should. And to be clear, I don't recall this happening in the first 6 months of ownership. So it may be more hardware than software, we will see.

I'm just posting this here for input to see if anyone else have ever had these issues with a GRT EFIS. If not for input, I hope you enjoy a decent, upside down, spring day in Michigan.

Be sure to watch in 1080P (if you can) so you can read things on the EFIS like heading, Flight Path Indicator, Pitch ladder, and the comparison Garmin G5 next to the EFIS.

https://www.youtube.com/watch?v=zRETOgzs_B0
 
Are you referring to you ADI appearing to show you nose high compared to the Garmin? You have the synthetic vision and your level line is the solid white horizontal line which is altitude dependent.
Just watching the video it appears normal. Am I missing some other problem?
Turn off the synthetic vision and I would guess the ADI’s will match.
 
I have a Grand Rapids sport as well and I?ve noticed after flying a series of lazy eights and Chantelle?s that the GRT sport still shows a 5-10 degree bank when I am actually wings level. The flight path vector has always been out to lunch on mine.

Let us know what you find out. Good luck.
 
If your TAS or magnetic heading are off it can have a significant effect on your FP vector display.
 
RV8iator said:
Are you referring to you ADI appearing to show you nose high compared to the Garmin? You have the synthetic vision and your level line is the solid white horizontal line which is altitude dependent.
Just watching the video it appears normal. Am I missing some other problem?
Turn off the synthetic vision and I would guess the ADI’s will match.
Click to expand...

Yes. And the solid white line has been set to the correct horizon with 8 degrees pitch ladder offset.

The problem you're looking at in the video is when I roll wings level from (almost) any manuever with banking or higher G's. At the end of the manuever when I'm wings level, the Garmin is dead nuts and the GRT is stuck in a 5-10 degree nose high or low attitude and, sometimes, up to a 10 degree bank, reference to that solid white horizontal line.

A good point to notice is around the 3:40 mark of the video. After the 4 point, I stay wings level for a few seconds and the attitude is nose low on the GRT. After a second or two of straight and level flight, the pitch indication on the GRT slowly corrects itself to actual level.

Same at the 4:00 mark. Roll wings level after a gentle wingover and the GRT is indicating nose high (I'm decending at almost 900 fpm) and a 5 degree left bank (wings level)
 
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Brantel said:
If your TAS or magnetic heading are off it can have a significant effect on your FP vector display.
Click to expand...

I spoke with Greg at GRT in person, TAS shouldn't have anything to do with the FP vector. It's using just Heading, Ground Track from your selected GPS Source, Attitude information, and ROC. He did mention magnetometer calibration but mine has been calibrated to a 1-2 degree error. The GRT Magnetometer only requires 5 degree error or less to provide accurate heading information.
 
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Jvon811 said:
Yes. And the solid white line has been set to the correct horizon with 8 degrees pitch ladder offset.
Click to expand...

The solid white line is actually your horizon line dependant on you actual altitude. It’s different from the pitch ladder offset in the set menu. At altitude in level flight your aircraft symbol will be centered on the white line, not the blue/brown line on the ADI. Look at your video at the 55 second point just before it switches after takeoff to higher altitude. You can see the white line just above the actual horizon yet the pitch is correct. The white line depicts the horizon level with your current altitude on the syn vis. But, I do see some lag on the pitch and roll and that isn’t right.

The problem you're looking at in the video is when I roll wings level from (almost) any manuever with banking or higher G's. At the end of the manuever when I'm wings level, the Garmin is dead nuts and the GRT is stuck in a 5-10 degree nose high or low attitude and, sometimes, up to a 10 degree bank, reference to that solid white horizontal line.

A good point to notice is around the 3:40 mark of the video. After the 4 point, I stay wings level for a few seconds and the attitude is nose low on the GRT. After a second or two of straight and level flight, the pitch indication on the GRT slowly corrects itself to actual level.
Click to expand...

Like Brian said, heading vastly effects the Flight path indicator and as does yaw and roll.
 
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I'm not trying to be rude, Jerry... And please forgive me if it seems that way, I'm just here to learn. But I know what you're saying, I know my equipment, and it's all set up correctly. It just doesn't sound like you see what's happening in the video.

I know the difference between my white horizon line and the Synthetic vision. I've seen the difference between the white line at sea level and on my many 12,500ft XC flights. That's not the problem at all. The only reason I mentioned pitch ladder offset is because I thought that's what you were inferring was that its was set incorrectly, it's not.

What happening is, after a maneuver, the white line is nowhere near correct to what I'm seeing visually outside the aircraft which is what the Garmin is correctly showing. The GRT EFIS is showing something different and will eventually "return to center" for lack of a better description as showing at the 3:40 mark in the video. The aircraft's real world attitude is (essentially) 0 Pitch, 0 Roll. Hence, my possible AHRS anomaly.

And I know that heading and yaw can greatly effect the FP indication. That's why I clarified my position that I was set up to well within GRT prescribed tolerances for getting the accuracy I expect. Not sure on the roll portion though... Unless you know something about the GRT programming that I don't. As from your avatar, you know an aircraft can be "rolled" in any direction and be traveling another.

The problem is there, I'm emailing with GRT to try and figure out why. I'm just posting here to see if it is happening/has happened to anyone else.
 
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Jvon811 said:
I'm not trying to be rude, Jerry... And please forgive me if it seems that way, I'm just here to learn. But I know what you're saying, I know my equipment, and it's all set up correctly. It just doesn't sound like you see what's happening in the video.

I know the difference between my white horizon line and the Synthetic vision. I've seen the difference between the white line at sea level and on my many 12,500ft XC flights. That's not the problem at all. The only reason I mentioned pitch ladder offset is because I thought that's what you were inferring was that its was set incorrectly, it's not.

What happening is, after a maneuver, the white line is nowhere near correct to what I'm seeing visually outside the aircraft which is what the Garmin is correctly showing. The GRT EFIS is showing something different and will eventually "return to center" for lack of a better description as showing at the 3:40 mark in the video. The aircraft's real world attitude is (essentially) 0 Pitch, 0 Roll. Hence, my possible AHRS anomaly.

And I know that heading and yaw can greatly effect the FP indication. That's why I clarified my position that I was set up to well within GRT prescribed tolerances for getting the accuracy I expect. Not sure on the roll portion though... Unless you know something about the GRT programming that I don't. As from your avatar, you know an aircraft can be "rolled" in any direction and be traveling another.


The problem is there, I'm emailing with GRT to try and figure out why. I'm just posting here to see if it is happening/has happened to anyone else.
Click to expand...

Not offended at all. Just clarifying. I?ve been using and representing GRT for years. They very graciously sponsored our team.
I?ve flown a couple thousand hours using their products, many of them very aggressive acro during shows and their stuff has been rock solid, and I?m sure they will get to the bottom of your problem. Jeff is the source to figure it out.
Keep us in the loop when you gt it figured out.
 
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