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GRT Sport EX display goes crazy once it sees static pressure???!!

Kooshball

Well Known Member
GRT Sport EX display goes crazy once it sees pitot pressure???!!

I?m in the final stage of install and testing on the panel upgrade which includes an AV-30, GRT Sport EX, ADSB in/out and MGL tach / MP.

All the wiring was done this week and all units behave normally except the GRT sport EX but only once it sees pitot pressure.

I setup a leaf blower to give 45-60 kts of airspeed into the pitot tube and then and only then did the GRT display start displaying all kinds of vertical lines. When airspeed is removed the display goes back to normal.

Has anyone here encountered this? If so, what was the problem and the solution?

Pic below and I have a video as well. Thx!

https://ibb.co/hVf8rL6

<a href="https://ibb.co/hVf8rL6"><img src="https://i.ibb.co/hVf8rL6/901113-F3-F239-4-ACC-8-D30-02-CC2-FF74-BA5.jpg" alt="901113-F3-F239-4-ACC-8-D30-02-CC2-FF74-BA5" border="0"></a>
 
Last edited:
Something's wrong

901113-F3-F239-4-ACC-8-D30-02-CC2-FF74-BA5.jpg
That does not look like anything I've seen before. I think you will need to call GRT Avionics on Monday.
 
Well, this sounds crazy! Is it possible the pitot line is connected to a vent on the efis, or maybe the pressure sensor is broken inside, so there?s a strong blast of air pushing on a ribbon cable somewhere? I?d start by pushing some vinyl tubing over the pitot tube, tape over the drain hole. Hold the tubing in a U shape, add some water, lift up the free end. If the water in the U stays level, you?ve got a leak. Step two. Same vinyl tube over pitot, no water. Bring the free end of the tube into the cockpit, gently blow while watching the efis. Still go crazy? Can you hear air leaking anywhere?
BTW I cannot see picture.
 
Is your leaf blower possibly electric? Looks to me like it could be interference from a nearby electric motor.
 
Is your leaf blower possibly electric? Looks to me like it could be interference from a nearby electric motor.

It is and we thought of that so we switched to compressed air from a distance so as not to damage anything. The same thing happened with compressed air. (The photo was actually of the compressed air failure mode) The AV30 behavior was normal in both cases.
 
The screen is showing multiple alarms, have you looked to see what they are??

Press the "MSG" button to see what is making the little gnome inside the box unhappy. You can then inhibit each item and see if the lines go away with one of them.

Might find the issue ---- might not, but probably worth a try.
 
Yes, just voltage below 12V alarm and no GPS2 signal since I had that off.

The screen is showing multiple alarms, have you looked to see what they are??

Press the "MSG" button to see what is making the little gnome inside the box unhappy. You can then inhibit each item and see if the lines go away with one of them.

Might find the issue ---- might not, but probably worth a try.
 
Since grt won?t be open until Monday, I?d pull it, take the cover off, and look around the airspeed sensor. Is there anything that moves? Are there any cables/connectors up against it? Gently push on the internal connectors, make sure they?re all seated.
 
Solved! It seems that there never really was an issue...when the unit sees airspeed but no GPS ground speed it gets confused and displays all kinds of obstacles which is what those lines are.

Too bad it can?t deal with that but I?m glad there isn?t an issue with the unit.

Thx for all the replies!
 
This is strange. I have a GRT Hx. I?ve tested the pitot using the Hx and a vinyl tube over the pitot, inside the hangar where there is no gps signal. I never see those lines. I do lose synthetic vision since it doesn?t know where it is.
 
strange

Solved! It seems that there never really was an issue...when the unit sees airspeed but no GPS ground speed it gets confused and displays all kinds of obstacles which is what those lines are....
Did they see that picture? It's hard to imagine that they would think this is normal...

I had a pitot static test done on mine inside the hangar and didn't see this. My hanger may have allowed some GPS signal in, since it's quite old, and has some plexi tiles for light.

I have not tested something like this while disconnecting the GPS antenna or covering it with multiple layers of something that will prevent a signal from coming in, but I might.
 
Did they see that picture? It's hard to imagine that they would think this is normal...

I had a pitot static test done on mine inside the hangar and didn't see this. My hanger may have allowed some GPS signal in, since it's quite old, and has some plexi tiles for light.

I have not tested something like this while disconnecting the GPS antenna or covering it with multiple layers of something that will prevent a signal from coming in, but I might.

Just to clarify...I am getting a GPS signal in the hangar...just no movement. When the issue starts you can actually see the flight path marker start moving and go off to the right then disappear as the bars show up.

GRT has seen the pic, a video and a few more pics and are telling me it is normal but it still seems strange.
 
The same happens to me. Seems the AHRS is confused when it gets airspeed data but the gps says it is sitting still. That?s different than losing gps altogether. The AHRS synthesizing a lot of data and freaks out when it doesn?t fit, apparently.

Not an issue in the air. I have lost gps in flight briefly and the display was rock solid.

Chris
 
do these lines show if you actually increase altitude?? The pic posted shows you're "flying low" so obstacles are an issue..
 
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