Garmin says the GSU25 should be mounted inline with the center line of the aircraft and on a rigid structure. I don't want to mount it on the back of the G3X because I don't want to have to disconnect the pitot static system to remove the G3X. A professional avionics installer told me he puts the unit in the gear tower, behind the top of the inboard face, which is angled. I am thinking about mounting it against the forward side of one of the gear towers, which I can easily access because I did the gear tower mod. That side is perpendicular to the centerline and the cockpit rails, so it's seems like a perfect place to put the GSU25. Any thoughts or experience with this?
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GSU25 mounted in gear tower
- Thread starter bmellis11
- Start date
Hi - I would follow the installation instructions as closely as possible.
I think a lot of people mount behind and attached to GDU. Why wouldn’t you do that?
If you use nylon tubing and nice pneumatic push on fittings it is simple and straightforward to connect and disconnect. At any rate, I don’t think you would be removing GSU25 or other G3X LRU very frequently. The only LRU not able to updated via the CAN bus is GTX45R (firmware) and maybe other GTX’s. For this you could have a cable attached to harness so dealer can update it without removal.
I have heard some on this forum say not to mount attached to GDU but they don’t advocate mounting in gear towers.
One thing is for sure and that is not to mount in enclosed spaces.
About a year ago there was a service bulletin or something like it instructing not to install GSU under floor or in other odd enclosed places because loud vibrations had led to GSU failure. I suppose enclosed spaces can amplify vibrations and sound.
Warm regards,
I think a lot of people mount behind and attached to GDU. Why wouldn’t you do that?
If you use nylon tubing and nice pneumatic push on fittings it is simple and straightforward to connect and disconnect. At any rate, I don’t think you would be removing GSU25 or other G3X LRU very frequently. The only LRU not able to updated via the CAN bus is GTX45R (firmware) and maybe other GTX’s. For this you could have a cable attached to harness so dealer can update it without removal.
I have heard some on this forum say not to mount attached to GDU but they don’t advocate mounting in gear towers.
One thing is for sure and that is not to mount in enclosed spaces.
About a year ago there was a service bulletin or something like it instructing not to install GSU under floor or in other odd enclosed places because loud vibrations had led to GSU failure. I suppose enclosed spaces can amplify vibrations and sound.
Warm regards,
Per Garmin, "mounting the GSU 25 to the threaded holes on the back of the GDU 4XX display is not generally recommended due to instrument panel flexing." They also say to perform a new pitot static check, pitch/roll calibration, magnetometer calibration, and several other tests each time you disconnect the tubing on the GSU 25. I want to be able to remove the GDU or panel if I need access behind the panel without having to do all those recalibrations. So I'm going to avoid mounting the GSU 25 there. In general they call for a rigid mounting location in line with the centerline of the aircraft.
I have read a lot of threads and people have had issues mounting this device throughout the aircraft.
The gear towers seem like a good place to mount it given Garmin's requirements. So I'm just trying to see if anyone has done it and can give advice about it.
Hi Ben -
I hope the gear tower solution works for you. I also hope you don’t have to go behind panel too frequently once you’re flying.
I think I have debugged all my wiring now so I am about ready to rivet my top fwd fuze.
I found it more convenient to mount behind GDU. The threaded holes are remarkably adaptable to GSU placement there.
It’s actually not too bad doing the calibrations. GSU aligns itself every power up and I calibrated my magnometer last week for first time and it took only a couple of minutes. G5 backup also aligns every power up.
It is true there is a bit of flex in my panel especially at the bottom of it. But I have some brackets supporting my GTN to subpanel so I don’t think it’s going to be too much of an issue.
I would like to see your build next time I’m in the city if you have time.
Warm regards,
I hope the gear tower solution works for you. I also hope you don’t have to go behind panel too frequently once you’re flying.
I think I have debugged all my wiring now so I am about ready to rivet my top fwd fuze.
I found it more convenient to mount behind GDU. The threaded holes are remarkably adaptable to GSU placement there.
It’s actually not too bad doing the calibrations. GSU aligns itself every power up and I calibrated my magnometer last week for first time and it took only a couple of minutes. G5 backup also aligns every power up.
It is true there is a bit of flex in my panel especially at the bottom of it. But I have some brackets supporting my GTN to subpanel so I don’t think it’s going to be too much of an issue.
I would like to see your build next time I’m in the city if you have time.
Warm regards,
fl-mike
Well Known Member
If you can flex it even a little bit, you will have issues. Been there, done that. Make it ROCK solid, and then brace it a bit more...
The gear tower is certainly a stout structure in that regard.
I'm not familiar with the gear tower construction of the -8 so I don't know exactly what you are referring to, but you might take a look at where it is installed on the RV-12. Not really something I would describe relative to anything landing gear related, but certainly not in the panel attached to other components. On the -12 is it mounted to a panel under the baggage floor, just forward of the rear baggage bulkhead.
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