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GTN650 installation considerations

Thanks, I’ll let them know. Sounds rather amateurish as an error?

There are a lot of avionic technicians that have been around a long time and do’t need to read no stinking install manual. :)

KUZA, United States

tomjnx wrote:

Seems they connected the CDI to VOR/LOC LEFT/RIGHT (P1004 5/6) instead of MAIN LATERAL LEFT/RIGHT (P1001 49/68)

Altough it is possible I would wonder why an installer would do this. It would also show up during post installation testing. It is more likely that an indicator with build in coverter is used.

Rwy20 wrote:

Can anyone tell me if this is an installation problem and what would be needed to correct it?

IMHO Changes are that your aircraft uses an indicator with build in converter. In that case, you would use one composit signal, instead of left / right lines. This system is only compatible with VOR/LOC, not with GPS. This system was used for example with KX-155 which only had composite output. So if the GTN replaced a KX-155 changes are big that the indicator is not useable for GPS.

In that case you would need another indicator. if you want to use this, or you should use the on screen CDI for GPS.

JP-Avionics
EHMZ

Jesse wrote:

IMHO Changes are that your aircraft uses an indicator with build in converter. In that case, you would use one composit signal, instead of left / right lines. This system is only compatible with VOR/LOC, not with GPS. This system was used for example with KX-155 which only had composite output. So if the GTN replaced a KX-155 changes are big that the indicator is not useable for GPS.

I think you hit the nail on the head, @Jesse – merci. Yes, the GTN replaced a KX-155, and before and after the change, the CDI needle showed some oscillations when tuned to a VOR, to the point that the plane sways around when you set the autopilot to follow NAV 1. The fact that this issue still persists after changing the VOR receiver proves that it must be an instrument with built in converter, and that the oscillations come from this converter. Time to change the CDI indicator, I would say.

Last Edited by Rwy20 at 29 Mar 09:09

It would seem me that the the first consideration for installing a GTN 650 would be to read & understand the install manual.

Why would you install the wrong type of indicator when you have gone to the expence of a GTN650 ?

Because it’s a VFR only club plane. The CDI was already installed and didn’t get changed. The radio had to be changed to comply with the 8.33 kHz mandate. But if you want to offer good rental rates, you only do the absolutely necessary at a time. Actually by just changing the radio, we didn’t lose any functionality, because this is the first time this plane has a GPS installed at all.

Compared to when I took my first flight on this plane, it is already luxurious now with an electrical system that works (before, the ammeter was oscillating wildly all the time and at one point, the alternator refused to work), a Mode S transponder, new interior, and a new windshield (before, it was scratched so that it was on the verge of becoming dangerous e.g. when flying into the sun). And we still flew through half of Europe VFR with that plane before all the upgrades. You can’t have a 180 PS Archer at 145 € wet and have the latest and greatest equipment all the time. Welcome to the french club scene.

But, as I wrote: “Time to change the CDI indicator, I would say.”, so I agree that this would now be nice to have. I also wouldn’t have chosen the “VFR only” version of the GTN650. Does anyone know if a possible upgrade to IFR is just a change in licensing that is done by buying some expensive paperwork, or do you have to change the hardware box?

Last Edited by Rwy20 at 29 Mar 10:47

I am going to guess that the VFR only apply to the basis of how it was fitted and not to the GTN650 box.

An example of this is the power supply has to have a TVS fitted in the IFR certified fit but not the VFR fit, the IFR version has to have an approved indicator. The IFR fit requires the GPS anttena to be fitted away from some other equipment, this is not a VFR requirement ( just a recommendation ).

All these issues are not expensive to achieve at inital fitting but are likely to involve a lot of labour if you find you need to install them.

Last Edited by A_and_C at 30 Mar 07:15
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