Vacuum to Glass - your thoughts on 2nd COM ?

[pagirard]

Hi everyone,

I'm the proud co-owner (since last week) of a '74 M20E currently equipped with :

• Vaccum gauges (6 pack)
• 530W + 430W
• Accutrack autopilot
• GTX 327
• Basic fuel and engine monitor by Electronic International

And we decided we want to go all in a glass panel overall:

• G3x + primary engine monitor
• G5 backup
• GFC500
• GNT750Xi + GMA35

to help with the cost, we are thinking to re-sell/trade in the 530W and 430W but if we do that we loose the backup GPS and the 2nd radio.

We would prefer to keep the panel "consistent" and trade in the 430w. What would you guys recommend for a 2nd COM unit ? Should we keep the 430W ?

 

Our goal/mission is to have a capable IFR cross-country plane to fly the family and create memories.

This is the current panel:

 

 

Thanks in advance for your help

 

Pierre

 

[carusoam]

Welcome aboard Pierre… (again). 

Adding a GTN with touch screen is all the rage nowadays…. 650txi…

Since your shopping list is all Garmin…

It makes a lot of sense to have everything be Garmin…

Garmin also has options for radios with various skills… if you don’t need all of the skills available with the GTN series…

 

MS Also has a few people that supply new hardware and are really good with answers…

MS also has a source for pre-flown avionics if interested….

Best regards,

-a-

[Seymour]

Interesting choices.   We're doing a similar update in our '65, but decided to go the dual GI275 route with the GTN650 Txi.   The 275 does have a VFR GPS with a glareshield antenna to use as a backup, but....

To make room for the GFC500 in our radio stack, we were planning to trade out our Narco NAV/COM for a GNC 255A NAV/COM (height difference).   The 255A has a longer lead time and the NAV portion as backup didn't really make sense (GTN650 is NAV/GPS/COM) so we've updated the plan to a GNC355A GPS/COM instead.   It provides one extra screen that can be used for traffic, Wx, or backup GPS.

Finally, we're keeping our vacuum AI (and functional step).    PM for more info if interested.   

Dave

[PeteMc]

I opted for the GNC355 as my Comm 2 and Backup GPS. 

But there's nothing wrong with keeping the 430W for now if you don't want to go all in on the upgrade.  Down the road a used GTN650Xi might come on the market and then you'll have a setup like you do now.

 

[ZuluZulu]

You didn't mention replacing the transponder, so how about a GNX 375 (#2 GPS navigator and MFD + transponder) and either a GTR 20 remote comm controlled through the G3X (might need approval for a certified installation, not sure) or the GTR 225 if you want something in the panel.  And if you want a NAV/COMM instead of just a COMM, the GNC 255 is a great radio.  That would give you two IFR GPSes, two COMMs, and either one or two IFR NAVs, plus an ADS-B transponder that can be controlled through the G3X.

[PeteMc]

41 minutes ago, ZuluZulu said:

so how about a GNX 375

Downside of the GNX is that it wouldn't give him the 2nd Comm he's looking for.

[McMooney]

As both radios are wass, I'd just keep the 430w and 530w, save those install dollars.

admit, there are nice new features in 750 but what a horrible price to pay.

g3x, g5 and gfc500 sound great.

eventually, i'm going 3x gi275.  (adi, hsi, engine monitor).  

was thinking g3x but installer started talking extra 0's.

 

 

 

[Mooney Dog]

In the modern(ish) world. GPS with a single nav with 2 coms is golden. 

 

I recently had my plane redone with dual g5s, a GNX 375, and a 255 nav/com unit. I have an old king unit for a second com and it works great. Given what you're doing getting a 225 com unit for Garmin would add in well with your upgrade path. 

My only complaint about the 700/600 series would be the fact that the connex is an extra feature that you must pay for. Where as with my 375 i can sync my ipad to the panel and move a flight plan over in 2 clicks. 

[RobertGary1]

Keep the vacuum attitude as a cheap backup. 
 

 

[hammdo]

Could swap the 430 and 530 for Avidynes - but buy those new. That way, you could trade the 430 and 530 in. If you go with  used Avidyne, make sure they are not blacklisted by Avidyne before buying...

Then you can decide on the main glass display...

Just an idea...

-Don

[PeteMc]

1 hour ago, hammdo said:

for Avidynes

There's another thread on how Avidyne "Black Lists" it units if the plane has been involved in any kind of incident.  And there isn't clear guidance on what the threshold is.  Sounded like even a gear up with no major damage to the plane would result with any Avidyne equipment going on their Black List, so no more support.  

At least that's how I read it.

[pagirard]

5 hours ago, hammdo said:

Could swap the 430 and 530 for Avidynes - but buy those new. That way, you could trade the 430 and 530 in. If you go with  used Avidyne, make sure they are not blacklisted by Avidyne before buying...

Then you can decide on the main glass display...

Just an idea...

-Don

Thanks for the suggestion Don but we are pretty set on getting only one manufacturer for autopilot, glass, NAV and COM to minimize the quirks and communications issues between devices.

[pagirard]

5 hours ago, RobertGary1 said:

Keep the vacuum attitude as a cheap backup. 
 

 

We considered it but it is very appealing to remove the entire vacuum system (pump and Mooney stabilization system) since we are going to put servos for the GFC500.

Also the G5 has a backup battery

[pagirard]

6 hours ago, Mooney Dog said:

In the modern(ish) world. GPS with a single nav with 2 coms is golden. 

 

I recently had my plane redone with dual g5s, a GNX 375, and a 255 nav/com unit. I have an old king unit for a second com and it works great. Given what you're doing getting a 225 com unit for Garmin would add in well with your upgrade path. 

My only complaint about the 700/600 series would be the fact that the connex is an extra feature that you must pay for. Where as with my 375 i can sync my ipad to the panel and move a flight plan over in 2 clicks. 

Humm, didn't know connex is a paying option in the 700 series - thanks for bringing this up

[pagirard]

8 hours ago, ZuluZulu said:

You didn't mention replacing the transponder, so how about a GNX 375 (#2 GPS navigator and MFD + transponder) and either a GTR 20 remote comm controlled through the G3X (might need approval for a certified installation, not sure) or the GTR 225 if you want something in the panel.  And if you want a NAV/COMM instead of just a COMM, the GNC 255 is a great radio.  That would give you two IFR GPSes, two COMMs, and either one or two IFR NAVs, plus an ADS-B transponder that can be controlled through the G3X.

So after some discussion with the avionics shop, they recommended a GTN 750Xi + GMA 35 (GPS, NAV1, COM1) and have the G3x control a GNA255 (NAV2, COM2)

 

Seems like it accomplish all we want and help us keep space on the right side of the panel for an iPad.

Thanks everyone for your contributions and your insights - much appreciated.

Pierre

PS: I found great comments and inspirations on this post as well

 

 

[RobertGary1]

48 minutes ago, pagirard said:

We considered it but it is very appealing to remove the entire vacuum system (pump and Mooney stabilization system) since we are going to put servos for the GFC500.

Also the G5 has a backup battery

AHRS can fail. I’ve had dual AHRS failure in my 275. So happy I had a vacuum backup. Garmin has released a couple patches for dual AHRS failure issues. 

[Mooney Dog]

1 hour ago, pagirard said:

Humm, didn't know connex is a paying option in the 700 series - thanks for bringing this up

Its really only helpful for that first 5 minutes of programing the GPS. The touchscreen 750 makes it really quick to enter in a flight plan, lightyears ahead from the 430s. It says its a $1,495 upgrade from Garmin's website, and it really is just a SD card...

 

[ZuluZulu]

On 3/1/2022 at 9:55 AM, PeteMc said:

Downside of the GNX is that it wouldn't give him the 2nd Comm he's looking for.

I recommended three different COMMs to mitigate that, which you left out of your quote.  Not exactly sure why, maybe I’m missing your point. In any event, his choice of the GNC 255 is a good one, I have the same radio!

[StevenL757]

18 hours ago, pagirard said:

Thanks for the suggestion Don but we are pretty set on getting only one manufacturer for autopilot, glass, NAV and COM to minimize the quirks and communications issues between devices.

Spot on.

[PeteMc]

1 hour ago, ZuluZulu said:

I recommended three different COMMs

Hmmm...  So did I have too much coffee or too little coffee that day.... 

[rbp]

20 hours ago, pagirard said:

So after some discussion with the avionics shop, they recommended a GTN 750Xi + GMA 35 (GPS, NAV1, COM1) and have the G3x control a GNA255 (NAV2, COM2)

 

I went for the GNC355 for the second GPS WAAS instead of a second NAV.  my rationale is that the likelyhood of a GPS outage simultaneously occurring when my GTN750 fails is low enough for my comfort, and VOR/LOC/GS is going to fade away the same way as ADF and LORAN.

[cujet]

I don’t care for vacuum driven instruments. Please don’t take my post as “ancestor worship”.

I’m simply pointing out some known downsides to TAA (technically advanced aircraft). The FAA recognizes TAA as having more “available safety”, while also recognizing that in many cases, glass cockpits reduce safety. The FAA has detailed statistics on takeoff, cruise, weather and landing accidents for TAA vs legacy aircraft, and it's nowhere near as promising as we'd like to think. Pilots are often unable to troubleshoot failures, there are often single points of failure, and so on. 

 

When the electrical smoke escapes (recently happened to me) the proper course of action in flight is to power down the aircraft. I suggest a backup instrument configuration that is 100% separate and independent (and if EFIS) on it's own battery. 

Our new Gulfstream G600 has 2 battery powered standby EFIS displays on the glareshield. Cool! Except, both LOSE airspeed and altitude information when main batteries are selected OFF. What engineer thought this was OK? Even the best designers and engineers can't seem to get everything right. 

As to whether a failure on TAA is more or less distracting is also the subject of FAA investigation. At the moment, it seems the answer seems to be “more distracting” and much more difficult to overcome.

Edited March 3, 2022 by cujet

[FlyinAggie14]

 

On 3/1/2022 at 10:17 PM, Mooney Dog said:

On 3/1/2022 at 9:02 PM, pagirard said:

Humm, didn't know connex is a paying option in the 700 series - thanks for bringing this up

Its really only helpful for that first 5 minutes of programing the GPS. The touchscreen 750 makes it really quick to enter in a flight plan, lightyears ahead from the 430s. It says its a $1,495 upgrade from Garmin's website, and it really is just a SD card...

You don't have to worry about connex if you you are going with the G3X Touch as the Bluetooth is built into the G3X and it communicates flight plans and such to the 750/650 navigator. It will also communicate all the adsb data to your Ipad for foreflight or Garmin pilot.

[Ragsf15e]

My personal thoughts are 2 comms, 1 gps and 1 nav radio are enough for ifr these days.  I do not want the nav and gps on the same box though.

So my personal dream option (without just putting in several -650txi $$) has a gnc-355 (gps/com) and an sl-30 or gnc-225 (nav/com).  
 

You can certainly still have a failure that takes out everything, but one box going out still leaves a solid precision* approach capability and comm radio in the other box.

*For whatever reason, LPV approaches on WAAS gps aren’t considered “precision” but they generally have the same mins as an ILS, so are comparable.

[carusoam]

+1 for having two ways to get within 200’ of the ground…  WAAS in one box, ILS in the other works…

This is important… if you have a radio failure above the clouds on a low IFR kind of day…

Not so important if you are a VFR only pilot….

PP thoughts only…
 

-a-