Drak130, I did my avionics upgrades over the 22 years that I've owned this airplane. When I bought it in 1998 there was a vacuum AI, DG and an old Apollo VFR GPS. In 2000 I replaced the GPS with an Apollo GX60 and in 2019 a Garmin GTN 650. I was uncomfortable with only one vacuum driven AI for IFR flight so I added a backup electric RC Allen AI somewhere around 2002. I wanted to back up both the power source and the instrument. When the original vacuum AI fails, my plan is to replace it with another Garmin G5 as a PFD. That will be a good time to get rid of the vacuum pump and electric AI since I'll have two G5s that back one another up. I don't have an autopilot so there's no need to keep the RC Allen AI.

It's a problem that many owners face when they own an aircraft for a long time. Do I replace one unit at a time to save money and deal with specific needs or do I replace a bunch of things all at once and spend a ton of money? Plus technology changes rapidly, even in aviation. I didn't want to spend a bunch of money on things that would be obsolete in a few years.

I flew a practice RNAV LPV approach into my home airport today with the G5 HSI. It worked great. I wasn't sure how I would like the vertical bar on the right side of the display with the magenta diamond marking the glide path vs. the GI 106B CDI crosshairs. However, it was very intuitive.

I'm loving the G5 HSI. It sure is nice not to have to worry about precession and the G5 HSI display is easy to read with all the key information on the main page. I expected the glide slope to appear at the initial approach fix but it didn't appear until the final approach fix so some step downs were still needed.

Instrument approaches sure are easy with the GTN 650 and G5. Not like the pre-GPS days when I got my instrument rating. It's a whole lot easier even than my old Apollo GX60. It tells you how to enter a hold for course reversal and when to make turns.

My next upgrade will be to switch out the 430W with the GTN 650. I have the GNX 375 which has worked great as a backup for the 430 and it is driving a 106. When I do the 430 to GTN upgrade I'm considering replacing the 106 with another G5. Probably overkill but at least everything will be of the same vintage

You can drive your G5 from two navigators

Interesting. Could you keep the 106 driven off the 375 with the ability to shift off the 106 and over to the G% incase of failure of the 430W.

I'm not sure about the technical capability to switch the 375 between the 106 and a G5. They're probably connected via the RS232 interface so an external switch would work. When I installed my G5 as an HSI to replace my old vacuum DG, the avionics shop said Garmin's G5 STC required that it be the primary external display for the GTN 650 and I had to remove the GI 106B. I think the STC is what you would be fighting with your proposed configuration. Better check with an avionics shop.

Data from two Garmin navigators actually go to the GAD29B via Airnc 429 protocol. It then travels to the G5s via Can network. Later revisions of the G5 install manual shows the two navigators to the 29B where earlier revisions did not. With two G5s there is a lot of backup there. Sell your 106a while there is still a strong market there.

Can an older Nav unit like a King KX-155 or Narco 12D be displayed on the G5 as a secondary source as well?

The G5 takes digital input only via the RS232, CAN bus or GPS Coax connections. The older Nav units are analog. You could connect an analog instrument to a serial analog-to-digital converter like this: http://www.canaanavionics.com/U1713.aspx but the software might not be compatible. Garmin makes some data bus adapters but they are not intended to connect to analog avionics like the KX-155. You could spend a lot of money trying to get the hardware and software to work together and it would probably be a field approval.

Well now, that's a whole lot more to consider than expected. But its flying right. Kind of funny actually. I have an electrical degree and one would think that would help make a lot more sense out of the technology associated with todays avionics.....not so much. I understand how it works but all the interconnectivity issues I'll need to spend some more time on. My second comm is the old 250 gps which needs to go as well. This discussion has been very helpful. I think I'm going to regroup and consider the must haves and nice to haves. And yes, next stop is to an avionics shop to better understand what can and can't be done with what I have and what I've been thinking about.

Different subject but I'm having Trickair 3000 skis installed on the plane in January. If anyone is interested, I can provide some pics and feedback on how well they perform. Andy, could you suggest a spot on the site to post that info.

Mike I'm in the same situation with a Garmin 250xl as second radio. Really thinking about replacing it with Garmin GPS 175. Gives me a second GPS input to the G5s. Have ILS on #1 which is 430W and the way things are headed I'm happy with one ILS radio and a couple that will display an LPV approach. The other reason is that my eyesight required a lot more light than it once did. I do well with the color screens but screens like the 250 and 300XL units which rely on contrast are becoming harder for me.

That's one of the reasons I went with the 375. I needed an updated transponder and wanted a GPS that would allow for redundant GPS based approaches. I can relate to the whole eyesight thing. The color screens are much easier to work with. You'll like the 175.

As far as I know they are full replacements for the 6 pack. I kept the other instruments anyway out of habit but the G5s are amazing.

Two G5s can replace the full six pack as long as there's no autopilot involved. Garmin's STC includes some restrictions when there's an autopilot. You may have to keep your turn coordinator.

I've used my G5 HSI in both HSI and PFD modes since you can easily switch between them. PFD mode has a lot of information on a relatively small display. I haven't flown much with airspeed, altitude and vertical speed tapes and I find them a little hard to adjust to compared to analog instruments. I also think the glide slope indicator is a little hard to interpret on the PFD but easy on the HSI. It's not as easy to include the PFD in my instrument scan since my brain has to interpret more data, but I think it would improve with use. Given the limited panel space in my airplane, the best solution for me is to replace the old vacuum AI with a G5 PFD and remove the backup electric attitude indicator and vacuum system components.

A vacuum pump and vacuum gyros were good ways to provide redundancy for electrical instruments before modern avionics since there were many things that could go wrong with an aircraft electrical system. These days instruments like the dual G5s with 4-hour backup batteries are much more reliable than vacuum pumps and provide a lot more situational awareness. Removing the vacuum system components will lighten the nose by about 20 pounds, which shouldn't be enough to worry about CG with a 180 hp Maule. It should also increase engine power slightly due to removal of the vacuum pump load. I'm not a fan of leaving inoperative components to save money so it will cost more to remove the vacuum pump, install a cover, remove the regulator, lines, filters and gauge.

You're not kidding with regards to the cost associated with removal of all the vacuum system related components. I had mine taken out when I upgraded tot the G5's. a bit more pricey than I had hoped. One issue I have had with the G5's is sensitivity to temperature. If I'm out on a remote lake ice fishing. when its time to go and the plane has been sitting out in 10 degree temps, the G5's have not come up until I've gotten the cabin warmed up. Deciding to retain a few of the analog instruments has turned out to be a benefit in a few situations. Aside from the temperature issue, both G5's have performed flawlessly. I'm also not a fan of the tape readouts but I'm sure that will change with time. Had my Biannual flight review today. Shot 4 RNAV approaches. G5's make things so much easier. Wasn't sure how I'd feel about them when having them installed but I'm certainly a fan after using them for a little over a year.