Does a G5 installation allow switched GPS input?

[johncuyle]

After attending the Northwest Aviation show I'm not so sure that the Skyview, which I had been hoping would be the way to go, is a good option for my plane.  I'm now considering G5 and GFC-500 as a possible option again.  One thing I'm curious about is whether it is possible to switch GPS inputs on the G5's.  If I have both a GTN750 and a GTN650, can I toggle which one is providing heading/ILS input to the G5?  Does anyone with a G5 installation have a secondary VOR/ILS indicator (e.g. GI-106B) installed as part of their panel, with a pair of G5 and a pair of GTN?

[kortopates]

After attending the Northwest Aviation show I'm not so sure that the Skyview, which I had been hoping would be the way to go, is a good option for my plane.  I'm now considering G5 and GFC-500 as a possible option again.  One thing I'm curious about is whether it is possible to switch GPS inputs on the G5's.  If I have both a GTN750 and a GTN650, can I toggle which one is providing heading/ILS input to the G5?  Does anyone with a G5 installation have a secondary VOR/ILS indicator (e.g. GI-106B) installed as part of their panel, with a pair of G5 and a pair of GTN?

I really doubt it. But check the install or pilots guide to find out. Regardless though that’s isn’t a real problem since a separate switch can be added to toggle between the two Nav sources. This is how I have my backup LSI-500 installed with both a GTN 750 and 650 since it only takes one Nav source by itself.


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[johncuyle]

Just now, kortopates said:

I really doubt it. But check the install or pilots guide to find out. Regardless though that’s isn’t a real problem since a separate switch can be added to toggle between the two Nav sources. This is how I have my backup LSI-500 installed with both a GTN 750 and 650 since it only takes one Nav source by itself.


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A separate switch or button would be fine by me.  Some of the Cessnas I trained in had a setup to toggle sources, IIRC.  There appears to only be a single serial input to the back of the unit, I think my avionics guy said it only allowed one input, but the pilot's guide table 2-1 Nav Source Annunciations lists:  

GPS/ GPS1/ GPS2
VLOC/ VLOC1/ VLOC2
VOR/ VOR1/ VOR2
LOC/ LOC1/ LOC2
 

Which makes it look like it can accept input from more than one GPS/NAV.  Except section 2.3 says it can only accept input from the #1 NAV.  Hopefully a toggle switch could be wired in.  It makes sense to me to be able to display nav from either nav on either display and to have two displays for the sake of redundancy, but maybe I'm just being paranoid.

[N201MKTurbo]

So which GPS input are you talking about? The G5 needs a GPS source to even run. It just supplies the basic position and heading information necessary to be an attitude indicator or DG. This input goes into the serial port on the DB9 connector. All the Nav data goes in via ARINC 459 through the GAD 29 AIRINC interface. I need to look at the STC install manual to see if it allows multiple nav sources and how they work.

I'll let you know.

[kortopates]

A separate switch or button would be fine by me.  Some of the Cessnas I trained in had a setup to toggle sources, IIRC.  There appears to only be a single serial input to the back of the unit, I think my avionics guy said it only allowed one input, but the pilot's guide table 2-1 Nav Source Annunciations lists:  
GPS/ GPS1/ GPS2
VLOC/ VLOC1/ VLOC2
VOR/ VOR1/ VOR2
LOC/ LOC1/ LOC2
 
Which makes it look like it can accept input from more than one GPS/NAV.  Except section 2.3 says it can only accept input from the #1 NAV.  Hopefully a toggle switch could be wired in.  It makes sense to me to be able to display nav from either nav on either display and to have two displays for the sake of redundancy, but maybe I'm just being paranoid.

Annunciations and inputs are two different things. Annunciations just allow it show what you have it connected too. Using a separate switch you’ll use the unnumbered annunciations just as I do. If you hardwired it to the #1, you’d use 1. That’s all it is - and same as my ESI-500.
It isn’t until you get into real glass PFD’s that you get multiple Nav sources e.g. G500 & Aspen.


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[N201MKTurbo]

I just looked through the install manual and it says it is a one to one ratio. It also says it must be hooked to NAV1. It seems like you could install two G5s one for each nav source, but it would probably need a field approval, which would probably be easy to get.

[johncuyle]

Cool, thanks for the info, everyone.

[MIm20c]

I think Steve from Garmin said that the unit itself can handle more than one input but the STC currently limits the unit. The HSI can switch between two nav sources (like the 750/650) and will show both (via RMI?) at the same time.  So at this time only the experimental version will select between sources but that could change next year or next week if Garmin wants to.  I’ll try to find the thread. 

[McMooney]

what didn't you like about the skyview ?

[bradp]

 Mlm20C is correct- you can wire I believe needs to be a dual G5 setup to receive two GPS navdata inputs (the wiring diagram and setup is in the experimental manual).  No switches needed.  The STC is the limitation. Not the box. 

Steve did clarify that for a single GNS or GTN feeding data to the G5 HSI you can be depicting VLOC primary data and simultaneously depict RMI data for GPS data, or vice verse, from the same navigator.  This feature was sufficient for my purposes.  

I looked into this issue previously- possible to wire a switch for RS-232 between two navigators.  Sure.  Pretty easy.  Legal per the STC? Maybe not.  Possible to wire a switch to go between the 10 wires of both airinc and rs 232  data between two navigators. Much more complex and not guaranteed to work.  Add in an autopilot interface and looking increasingly more troublesome and less practical. 

i think they were aiming for a king HSI replacement in the G5, not an aspen or G500 competitor.   

[johncuyle]

McMooney: The things I didn't like about the Skyview were: 

• Might not be available before 2020.
• STC might not allow it to interoperate with an ADSB solution other than the included one (it hurts the value prop quite a bit if I install a GTX-345R just to need to use Dynon's solution a year later, plus I kind of want the integration with the Nav.)  I specifically asked about this and they told me they weren't sure, it depended on the FAA. 
• Need to use their installer. (May not be a problem, they say there will be a local shop and if it is the one I think I would be happy to have them do avionics work on my plane)
• Can't do portrait mount of the screens.  This is actually kind of a big one since I kind of wanted to do multiple screens and I don't think there's room to mount a screen to the right of the radio stack in landscape orientation.

bradp:  Noted.  I hadn't actually been considering the G5 seriously because I was pulling for the Dynon solution.  The G500 is too expensive to justify for my airframe.  The Aspen is too old for me to put the kind of money they want into it.  G3X Certified would be ideal but I wouldn't expect them to certify it and risk cannibalizing G500 sales unless they decide that the choice isn't "sell a G500 or sell a G3X", it's "sell a G3X or watch Dynon sell a Skyview".  It is probably sufficient for me to just have Nav 1 wired to a pair of G5 and Nav 2 wired to a separate indicator with no switch.  That's what I've got now and a pair of G5's with the batteries and a standby alternator plus a GFC-500 would be a huge improvement over the vacuum/single alternator KFC-200 setup I've got now.  It's just that I'd be a lot happier paying somewhat more to get a decent glass cockpit.  Unfortunately the only option is to pay a vastly more to get an overkill glass cockpit.

Edited March 14, 2018 by johncuyle
spelling

[DOCCOUNTRY]

I just took a test flight with my new installation of a pair of G5s in my M20E,  one came with GAD29 set up as the HSI and the other was for Attitude indicator.  The navigator is a 400w.  It went into the space vacated by the Narco ADF.   I will ask the shop if they know about separate selection of GPS .  I did not see it in the configuration mode but I was not looking for that.  Both can be toggled to the other instrument without loss of displayed data. I think it must be some kind of daisy chain to the 400w.   We could not display my narco VORs on the HSI so it is a dedicated gps instrument.     Is the desired multiple GPS input capability so that there is redundancy for failure or what is the operational need for the second gps input?    ( I am just getting my first and now I may want two :-) ) 

 

DC

[carusoam]

Welcome aboard, DC...

 

On the topic of switching nav sources...  early 90s Mooneys with an HSI used a simple looking switch to flip flop from enroute GPS navigation to using the precision of the ILS.  Nav1A and nav1B.

Nav2 was a second navcom with its own VOR indicator.  A Nav3 was the ADF with its own dedicated display.

The simple looking nav source switch isn’t so simple in the back.  It is a very reliable switch, with several wires being switched... radio shops will be familiar with this type of switch.

Probably more reliable if the switch is part of an electronic HSI...

PP thoughts only, not a radio technician...

Best regards,

-a-