Garmin dual attitude indicator failures with data

[RobertGary1]

Just an update I got a call from a senior Garmin guy. Garmin is very interested in this and have been research it. They want to schedule me to bring the plane into a dealer to get data off of it. One thing Garmin said is that they do use airspeed to correct from AHRS drift. But that if the airspeed is unavailable they will use GPS. I'm wondering if the winds were too strong for ground speed to be good enough to make that correction. I'm updating the logs from teh GI-275 here. You can see that as soon as I hit 100knots ground speed on departure I lose all AHRS data. Later on it comes back (although the attitude indicator was not correct) but then shortly there after it went out again.

log_210519_002921______.csv

[midlifeflyer]

Hope Garmin can figure out what's going on.

[GeeBee]

You have some pretty wild EPEs on your GPS data, interestingly close to the same lat/long

 

[Yetti]

6 hours ago, RobertGary1 said:

Just an update I got a call from a senior Garmin guy. Garmin is very interested in this and have been research it. They want to schedule me to bring the plane into a dealer to get data off of it. One thing Garmin said is that they do use airspeed to correct from AHRS drift. But that if the airspeed is unavailable they will use GPS. I'm wondering if the winds were too strong for ground speed to be good enough to make that correction. I'm updating the logs from teh GI-275 here. You can see that as soon as I hit 100knots ground speed on departure I lose all AHRS data. Later on it comes back (although the attitude indicator was not correct) but then shortly there after it went out again.

log_210519_002921______.csv 581.27 kB · 2 downloads

your 100 knot theory is bust.   Looks like attitude data stops recording 3 times.  Going over 100knots was one of the first times.  But that did not happen the second or third time.

You maintain your 3d GPS fix the whole time.    bug in the attitude section of the code.

[Ragsf15e]

7 hours ago, RobertGary1 said:

Just an update I got a call from a senior Garmin guy. Garmin is very interested in this and have been research it. They want to schedule me to bring the plane into a dealer to get data off of it. One thing Garmin said is that they do use airspeed to correct from AHRS drift. But that if the airspeed is unavailable they will use GPS. I'm wondering if the winds were too strong for ground speed to be good enough to make that correction. I'm updating the logs from teh GI-275 here. You can see that as soon as I hit 100knots ground speed on departure I lose all AHRS data. Later on it comes back (although the attitude indicator was not correct) but then shortly there after it went out again.

log_210519_002921______.csv 581.27 kB · 5 downloads

So if I lose electrical power in the soup, my battery backup G5s will still have power, but I’ll auger in with a big red X on them because my GPS input will drop and my pitot will ice up with no heat.  Great.

[Will.iam]

43 minutes ago, Ragsf15e said:

So if I lose electrical power in the soup, my battery backup G5s will still have power, but I’ll auger in with a big red X on them because my GPS input will drop and my pitot will ice up with no heat.  Great.

Well at least you know about this limitation now. So there’s that,,,, (in my best bill murray accent)

[Yetti]

2 hours ago, Ragsf15e said:

So if I lose electrical power in the soup, my battery backup G5s will still have power, but I’ll auger in with a big red X on them because my GPS input will drop and my pitot will ice up with no heat.  Great.

GPS did not drop out.  IT had a 3d fix the whole time.  And vertical speed data.   The attitude section went away for a bit.   If you have million parts with a MTBF of 1 million hours built into say a M1 tank, you should expected the tank to fail every hour on average

 

[LANCECASPER]

1 minute ago, Yetti said:

 If you have million parts with a MTBF of 1 million hours built into say a M1 tank, you should expected the tank to fail every hour on average

 

That describes the American car industry from the mid 70’s to the early 80’s, only it was a couple thousand parts, each with a MTBF of a few hundred hours . . Lol

[Yetti]

22 minutes ago, LANCECASPER said:

That describes the American car industry from the mid 70’s to the early 80’s, only it was a couple thousand parts, each with a MTBF of a few hundred hours . . Lol

PRetty much.   and now there is a chip shortage so nothing to write bad code against.

[RobertGary1]

29 minutes ago, Yetti said:

GPS did not drop out.  IT had a 3d fix the whole time.  And vertical speed data.   The attitude section went away for a bit.   If you have million parts with a MTBF of 1 million hours built into say a M1 tank, you should expected the tank to fail every hour on average

 

That wasn't my scenario but it is a good question. If you lose ship electrical will the attitude in the GI-275 and G-5, GX-3, G500, etc go out without pitot heat and GPS input?

-Robert

[Yetti]

32 minutes ago, RobertGary1 said:

That wasn't my scenario but it is a good question. If you lose ship electrical will the attitude in the GI-275 and G-5, GX-3, G500, etc go out without pitot heat and GPS input?

-Robert

You never lost Groundspeed (GPS)  or Pressure Alt  (At least reporting to the log file)   You did lose being able to see speed on the screen.

[RobertGary1]

Just spoke with Garmin and provided the logs. One thing they did say is that if you do not install the separate "VFR" GPS antenna on the GI-275's and you were to lose airspeed and GPS at the same time (i.e. lost of electrical system including pitot heat) the AHRS will fail. so if you fly in the clouds a lot you may want to consider the dedicated antenna. 

That isnt' my scenario as my GPS signal shows strong (3D) the entire time but something to consider.

[carusoam]

Great reporting RG1!

Keep up the good work...
 

Where is Peter lately?

With his love for the mechanical watches over the Casio variety...

The Red Xs on various electronic displays are becoming a bit more frequent....

Best regards,

-a-

[EricJ]

40 minutes ago, RobertGary1 said:

Just spoke with Garmin and provided the logs. One thing they did say is that if you do not install the separate "VFR" GPS antenna on the GI-275's and you were to lose airspeed and GPS at the same time (i.e. lost of electrical system including pitot heat) the AHRS will fail. so if you fly in the clouds a lot you may want to consider the dedicated antenna. 

That isnt' my scenario as my GPS signal shows strong (3D) the entire time but something to consider.

I've been thinking of putting just a cheapie GPS antenna from Amazon on my G5 and leaving it on (or under) the glareshield for this reason.    The specs for the antenna can be met with inexpensive units, but I haven't tried it yet.

[Yetti]

24 minutes ago, EricJ said:

I've been thinking of putting just a cheapie GPS antenna from Amazon on my G5 and leaving it on (or under) the glareshield for this reason.    The specs for the antenna can be met with inexpensive units, but I haven't tried it yet.

This is what gets me is a UBLOX 7 has more accuracy that the IFR GPS  and it is $7  or 2 for $14.     Dynon does all the GPS part in the antenna box.   Then just sends the sentences via serial to the units.    Easier to run as no coax.   Just 4 wires.  Power and serial.

[GeeBee]

3 hours ago, RobertGary1 said:

Just spoke with Garmin and provided the logs. One thing they did say is that if you do not install the separate "VFR" GPS antenna on the GI-275's and you were to lose airspeed and GPS at the same time (i.e. lost of electrical system including pitot heat) the AHRS will fail. so if you fly in the clouds a lot you may want to consider the dedicated antenna. 

That isnt' my scenario as my GPS signal shows strong (3D) the entire time but something to consider.

Again, look at your GPS EPE. You got some huge numbers there.

 

[RobertGary1]

5 minutes ago, GeeBee said:

Again, look at your GPS EPE. You got some huge numbers there.

 

Not sure which column that is. I see the accuracy says "3DDiff". (ignoring the initial minutes after start up before runup when the GPS expectedly doesn't have signal).

[PeteMc]

1 minute ago, RobertGary1 said:

...ignoring the initial minutes after start up before runup...

By any chance did you start taxiing before you got the 3DDiff?  I don't know about the 275, but there is an Advisory out for the GTN:

Taxiing before the ADS-B GPS source has calculated an acceptable GPS position, will result in an incorrectly transmitted “airborne” Air/Ground status.

[RobertGary1]

Just now, PeteMc said:

By any chance did you start taxiing before you got the 3DDiff?  I don't know about the 275, but there is an Advisory out for the GTN:

Taxiing before the ADS-B GPS source has calculated an acceptable GPS position, will result in an incorrectly transmitted “airborne” Air/Ground status.

 I do always do that. It takes about 3-4 minutes before it gets a gps lock and I don't usually sit around waiting for it. Do others? 

-Robert

[MikeOH]

9 hours ago, Ragsf15e said:

So if I lose electrical power in the soup, my battery backup G5s will still have power, but I’ll auger in with a big red X on them because my GPS input will drop and my pitot will ice up with no heat.  Great.

Hmm, I think I'm happy that I've stuck with my stone age AI (with three moving parts) and electric TC (which drives the STEC).  As a career EE all this reliance on electronics scares the crap out of me

[Marauder]

Peter Garmin always seems to miss out on these threads.


Sent from my iPhone using Tapatalk Pro

[Yetti]

4 hours ago, PeteMc said:

By any chance did you start taxiing before you got the 3DDiff?  I don't know about the 275, but there is an Advisory out for the GTN:

Taxiing before the ADS-B GPS source has calculated an acceptable GPS position, will result in an incorrectly transmitted “airborne” Air/Ground status.

Seriously?   That is a bad idea

[Ragsf15e]

8 hours ago, EricJ said:

I've been thinking of putting just a cheapie GPS antenna from Amazon on my G5 and leaving it on (or under) the glareshield for this reason.    The specs for the antenna can be met with inexpensive units, but I haven't tried it yet.

I’m definitely thinking of it now too... however, I cycled my HSI G5 to its internal gps with the 430w off and it picked up gps... 

[EricJ]

1 hour ago, Ragsf15e said:

I’m definitely thinking of it now too... however, I cycled my HSI G5 to its internal gps with the 430w off and it picked up gps... 

I've heard that they have an internal antenna, which in most Mooney panels under the windscreen and glareshield should have reasonable reception.

[jetdriven]

They don’t