What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Garmin GSU 25 (AHARS) failed vibration test

flysrv10

Well Known Member
My newly installed Garmin G3X system fails the vibration test. The AHARS (GSU25) is mounted as recommended by Garmin on the sub panel, right in front of the pilot near the top skin. Mounted as sold as a rock. I can shake the plane by holding onto it. Can any RV10 guys share an installation pic to compare? Any one has had this issue with suggestion for resolution? Thank you.
 
You should really run that by Garmin, they know best. Most of us have it mounted on the back of the G3X without any issues.

Garmin is great, but nobody is perfect. It's possible you got a bad unit. I had a bad GMU-11 that caused me grief (... determined only after pulling the airplane around the tarmac in 105 degree weather for 3 hours trying to calibrate it).
 
You should really run that by Garmin, they know best. Most of us have it mounted on the back of the G3X without any issues.

Garmin is great, but nobody is perfect. It's possible you got a bad unit. I had a bad GMU-11 that caused me grief (... determined only after pulling the airplane around the tarmac in 105 degree weather for 3 hours trying to calibrate it).

I have been talking to them but I hate to say, they are slow in responding. I am traveling for the summer and due to this issue, I am unable to file IFR.

Thanks for sharing your installation location.
 
I've seen something as simple as loose connectors on the GSU cause issues.
It would have to be seriously out of balance for a prop imbalance to cause that.
 
I've seen something as simple as loose connectors on the GSU cause issues.
It would have to be seriously out of balance for a prop imbalance to cause that.

Thanks Walt. All connectors tight as tik. All bolts tight. Wires supported.

My plane runs pretty smooth but I figured prop balance will eliminate one possibility and it can't hurt.

I have pulled the prop control and induced significant vibration in flight and the EFIS does not revert.

Must be an art to locate this thing.
 
Some engines will shake as they come up from idle to say 1200-1500, have you tried just running the vib test as around 1200-1500 or above so the motor is running smoothly? Some engines just idle badly for one reason or another (prob mixture or ign prob).
 
Some engines will shake as they come up from idle to say 1200-1500, have you tried just running the vib test as around 1200-1500 or above so the motor is running smoothly? Some engines just idle badly for one reason or another (prob mixture or ign prob).

I took off on partial power and the efis did not fail. Don’t recall the rpm setting possibly a little more than 50% power. I have surely so the plugs are all good, idles well. I do notice less vibration with the top cowl off. Also it passes the test with top cowl off at full power.
 
here's a picture...

Here is where I mounted mine...


display_log.php



FP29102019A0000F.jpg
 
Last edited:
I do notice less vibration with the top cowl off. Also it passes the test with top cowl off at full power.

Interesting. I plan on mounting my GSUs in the same spot. Do you have adequate clearance between the cowl edge and fwd fuselage skin? Or is your baffling making any contact to the cowl? Seems like there's vibration being transferred there.
 
Interesting. I plan on mounting my GSUs in the same spot. Do you have adequate clearance between the cowl edge and fwd fuselage skin? Or is your baffling making any contact to the cowl? Seems like there's vibration being transferred there.

I have good clearance between the cowl and fuselage. Don't feel excessive vibration, nothing more than any other RV I have flown. Garmin sez it is an "unusual" case.

If you want to be safe, I recommend that you fabricate the harness so you can locate it on the back of the unit if your choice location does not work. I cannot relocate mine due to harness length. Or wait for a couple of weeks until I install my replacement GSU and report back.
 
I've never mounted a GSU25 on the back of a GDU, and never had a problem with any of them. Mounting on the back of a GDU makes access behind the screen so much harder and impractical I would never do it.
 
I've never mounted a GSU25 on the back of a GDU, and never had a problem with any of them. Mounting on the back of a GDU makes access behind the screen so much harder and impractical I would never do it.

I agree. I did not locate it on the back of the 460 for the same reason.
 
The GDU comes out of the panel with 4 screws easily taken out while sitting on your nice comfortable seat.
 
Location...Location...Location

Not to be contrarian -- oh who am I kidding...

I put mine on the back of the GDU 460; Vibration survey passed at all engine RPM from 1000 to 2700, go figure.

Easy access too..

Sort of like telling bumble bees that they cannot possibly fly..
 

Attachments

  • IMG_0161.jpg
    IMG_0161.jpg
    278.3 KB · Views: 127
I think

I think that garmin cautions against mounting it on the gdu due to the possibility of vibration if the gdu is not adequately supported in the panel. This doesn’t seem to be a problem in the RV aircraft as the instrument panel is pretty solid. I have talked to a bunch of folks who mounted on the gdu with no issues...
 
But there are also those of us with mounts to the back of the G3X who do have vibration issues (periodic ADAHRS reversion and reboot) that Garmin blames on the location.
 
GSU25

I would really really like to mount mine to the back of the GSU. It will leave me more room for the voltage regulator. Curious how many people have done this. Maybe it is time for a poll???
 
I would really really like to mount mine to the back of the GSU. It will leave me more room for the voltage regulator. Curious how many people have done this. Maybe it is time for a poll???

I put mine there when I saw that Mitch Lock put it on the back of the GDU when he was building what would become the East Coast demo plane. As far as I know, that plane has never had an issue, nor I on mine.
 
My feeling is that if you are sure that the screws are tight, the only other option is that you have bad unit.
 
I have good clearance between the cowl and fuselage. Don't feel excessive vibration, nothing more than any other RV I have flown. Garmin sez it is an "unusual" case.

If you want to be safe, I recommend that you fabricate the harness so you can locate it on the back of the unit if your choice location does not work. I cannot relocate mine due to harness length. Or wait for a couple of weeks until I install my replacement GSU and report back.

Got a new GSU25 and a roll servo. Apparently the roll servo was doing something weird on the network.

I still don't pass the vibration test but I no longer have G3X command a right steep climbing turn right at take off as it was happening with the old GSU25.
 
Back
Top