I fear I've created a monster!

Will Kumley

Will Kumley

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Aug 6, 2019
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Will
Our new to us 1964 Piper Colt needed a new battery. Instead of just replacing it with the same type/model/series the wife opted to upgrade to a battery with better reviews from other pilots and shaved 15 pounds off our total airplane weight. Now she's thinking of other improvements we can make and I'm trying to keep things realistic, cost effective, and also not go nuts in the first year of ownership.

The picture below is the current panel. The AI, DG, and T&B are all vacuum driven off of a venturi system. Try as I might, this setup isn't great. The vacuum produced by the venturi is minimal (2-3" Hg). We've already checked the hoses and fittings. Although we found a missing hose clamp, it has made no impact on the vacuum pulled through the instruments at speed. I was considering installing a traditional vacuum pump as the plane did have it early in its life. This option is the cheapest option with minimal W&B impact but of course, everyone seems to be upgrading to digital and ditching their vacuum systems. After the battery upgrade the wife is now asking for options to upgrade the panel instruments/vacuum system and curious which route is ideal for us.

What feedback would you have in this situation?
Option A) Ditch the venturi, add a vac pump, new hoses, etc... Pros: Cheapest, relatively easy install, able to be done on field with my A&P/IA. Cons: maintains old instruments, will require regular maintenance on the vac pump, T&B may be non-working so it may need to be replaced regardless of which option we go with.
Option B) Remove vacuum system completely, install dual Uavionix AV-30s with the newly certified magnetometer. Pros: Improved instruments with digital info, may shave some weight off the plane. Cons: Cost, likely will need to be installed by an avionics shop which could result in more downtime.
Option C) Same as option B but with dual G5's. Pros/Cons remain the same.
** While I love the look of the GI275's I don't think I can justify the increased cost from the G5s considering what I'd be using them for. There will likely never be an autopilot installed in this plane.

End goal for the panel is to ultimately have IFR capability with a GPS navigator, Comm that allows me to monitor a 2nd freq, maybe upgrade the transponder to incorporate the ADSB-out requirement into it. Currently ADSB is accomplished via a skybeacon wingtip light and it works well with the existing transponder.
 

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I'd say go for the G5's. The AV-30's are still fairly light in features (such as being able to use them as a CDI/HSI for IFR navigation). I don't believe in buying something for what it _might_ do in the future. Yes uAvionix says they are going to offer that, but there is no guarantee. I like the look of them, the price and the possibilities, but I personally wouldn't spend the money on them today if you want IFR capability now or in the future (never know what kind of certification wall, software/hardware limits they might hit trying to deliver their intended goals). The G5 will do that today. Both the AV30's and the G5's should be able to be installed by your A&P/IA if they have the crimpers and skills (it's not rocket surgery), they are available for sale over the counter without being installed at an avionics shop. Based on your end goal, I'd really recommend a GNX375 and a GNC255. You'd get ADS-B in/out, WAAS IFR GPS, VHF NAV/COM with monitor capability, plus the GNC can provide the intercom functionality, so no need for a separate box for that (or an audio panel). You'd have a full IFR stack with full approach capability (LNAV/VNAV, LPV, ILS, VOR) in 2 devices.
 
I think this is a personal decision…but if it was MY personal decision, I would just add the vacuum pump. To me, putting that much money into a Colt is the equivalent of dumping a ton of money into a house that’s in a crappy neighborhood… you may like the result, but when it’s time to sell, it’s gonna hurt.
 
Ryan Klems said:
I'd say go for the G5's. The AV-30's are still fairly light in features (such as being able to use them as a CDI/HSI for IFR navigation). I don't believe in buying something for what it _might_ do in the future. Yes uAvionix says they are going to offer that, but there is no guarantee. I like the look of them, the price and the possibilities, but I personally wouldn't spend the money on them today if you want IFR capability now or in the future (never know what kind of certification wall, software/hardware limits they might hit trying to deliver their intended goals). The G5 will do that today. Both the AV30's and the G5's should be able to be installed by your A&P/IA if they have the crimpers and skills (it's not rocket surgery), they are available for sale over the counter without being installed at an avionics shop. Based on your end goal, I'd really recommend a GNX375 and a GNC255. You'd get ADS-B in/out, WAAS IFR GPS, VHF NAV/COM with monitor capability, plus the GNC can provide the intercom functionality, so no need for a separate box for that (or an audio panel). You'd have a full IFR stack with full approach capability (LNAV/VNAV, LPV, ILS, VOR) in 2 devices.
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Good point on the CDI/HSI ability of the AV-30 vs G5. I actually think the most difficult part of either will be finding a good location for the magnetometer considering its a steel tube and fabric airplane. The fabric is in great shape so I'm not too keen on the idea of cutting into it on the wings for an install.
 
Country Flier said:
I think this is a personal decision…but if it was MY personal decision, I would just add the vacuum pump. To me, putting that much money into a Colt is the equivalent of dumping a ton of money into a house that’s in a crappy neighborhood… you may like the result, but when it’s time to sell, it’s gonna hurt.
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Definitely a consideration I'm having. Although if I'm talking about adding a GPS nav unit and making it IFR capable this plane is already headed down a path of possibly more upgrades than make sense to some. Our kids are grown so as long as we can resist the urge to get a faster plane, I could see us hanging onto it for quite some time which makes the sting of an avionics upgrade less impactful.
 
Will Kumley said:
Definitely a consideration I'm having. Although if I'm talking about adding a GPS nav unit and making it IFR capable this plane is already headed down a path of possibly more upgrades than make sense to some. Our kids are grown so as long as we can resist the urge to get a faster plane, I could see us hanging onto it for quite some time which makes the sting of an avionics upgrade less impactful.
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Then it may make more sense to go the G5 route. I’m not trying to dump on the Colts either. I think they’re a great plane, they’re just typically more used for IFR training before a person upgrades aircraft once they get their ticket.
Keep in mind though, that getting an auto pilot might be impossible. I’m not sure if anyone makes one for a colt. Most people pretty much demand an auto pilot when flying any moderate level IFR.
 
The question becomes whether to spend a bunch of money putting lipstick on a pig (NO your airplane is not a pig). Or sell your currennt plane and get one more suited to IFR flying, including better panel and avionics.

In general, you may get 1/2 of the cost of new avionics when you sell. Or IOW, you only pay 1/2 the costs of new avionics when you buy a plane with them installed.
 
Country Flier said:
Then it may make more sense to go the G5 route. I’m not trying to dump on the Colts either. I think they’re a great plane, they’re just typically more used for IFR training before a person upgrades aircraft once they get their ticket.
Keep in mind though, that getting an auto pilot might be impossible. I’m not sure if anyone makes one for a colt. Most people pretty much demand an auto pilot when flying any moderate level IFR.
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Yep, I also don't think an autopilot exists for any of the Tri Pacer aircraft. Ultimately, we just want something that I can train for IFR in and use minimally to get in or out when the weather isn't terrible but also isn't VFR.
 
Pinecone said:
The question becomes whether to spend a bunch of money putting lipstick on a pig (NO your airplane is not a pig). Or sell your currennt plane and get one more suited to IFR flying, including better panel and avionics.

In general, you may get 1/2 of the cost of new avionics when you sell. Or IOW, you only pay 1/2 the costs of new avionics when you buy a plane with them installed.
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I've always heard to buy the plane with the avionics you want. But in todays market that's dang near impossible. We chose to buy a plane that appears to be well taken care of with a solid engine. Part of the reason I'm not really entertaining any discussions with the wife to go full bore on the avionics is because I want to ensure we have time on the plane and an annual completed before we go nuts. Also, the plan is to keep this plane for a while.
 
I wouldn’t even bother with adding a vacuum pump, the Venturi is fine for VFR flying.

if you are going make it at least a minimal IFR airplane then I would use the G5s as it works best for the HSI With the GPS, I don’t think the AV30’s do this yet.
Brian
 
brcase said:
I wouldn’t even bother with adding a vacuum pump, the Venturi is fine for VFR flying.

if you are going make it at least a minimal IFR airplane then I would use the G5s as it works best for the HSI With the GPS, I don’t think the AV30’s do this yet.
Brian
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If the venturi actually created enough vacuum this wouldn't be a discussion yet. The current venturi only pulls 2-3" of vacuum at 80+ MPH IAS. The AI and DG both require 4.5" of vacuum to operate correctly. The T&B doesn't have a label showing required vacuum but it has its own regulator to prevent getting overdriven from too much vacuum.

The dual G5 setup sounds like an easy, although not cheap, way to correct the non effective vacuum while also allowing for future upgrades.
 
To be fair, the more I look at prices and the fact that I don't want to spend a ton before the first annual I'm thinking a vacuum pump could be a good solution for now. However, the financial part of me hates the idea of buying something knowing I'll likely replace it in a few years.
 
Will Kumley said:
To be fair, the more I look at prices and the fact that I don't want to spend a ton before the first annual I'm thinking a vacuum pump could be a good solution for now. However, the financial part of me hates the idea of buying something knowing I'll likely replace it in a few years.
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No matter what solution you choose, you’ll likely replace it in a few years. If you got an electric T&B, would that reduce the demand on the Venturi enough to make it useful for the other instruments?

Will Kumley said:
Ultimately, we just want something that I can train for IFR in and use minimally to get in or out when the weather isn't terrible but also isn't VFR.
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In my experience, people who describe this sort of “light IFR” mission wind up being VFR only or getting themselves in serious trouble. If you aren’t starting out gung-ho for instrument flight, excited about breaking out at minimums after a couple of pleasant hours on top, maybe you should reconsider the IFR portion of your plan. It’s a lot of work to get the rating and, if you’re going to “use [it] minimally,” you’ll have a hard time keeping current and a very hard time staying proficient.
 
Do you have to install an electric turn and bank to run dual G5's? I'm not sure, maybe worth looking into.
 
farangutan said:
Do you have to install an electric turn and bank to run dual G5's? I'm not sure, maybe worth looking into.
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If you want to ditch the vacuum system and you have a vac driven T&B, then you need to replace with an electric T&B.
 
TCABM said:
If you want to ditch the vacuum system and you have a vac driven T&B, then you need to replace with an electric T&B.
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Not if you have dual G5s. They count, and each serves as backup for the other.
 
Will Kumley said:
If the venturi actually created enough vacuum this wouldn't be a discussion yet. The current venturi only pulls 2-3" of vacuum at 80+ MPH IAS. The AI and DG both require 4.5" of vacuum to operate correctly. The T&B doesn't have a label showing required vacuum but it has its own regulator to prevent getting overdriven from too much vacuum.

The dual G5 setup sounds like an easy, although not cheap, way to correct the non effective vacuum while also allowing for future upgrades.
Click to expand...

Sounds like you have a 4"Hg Venturi and need a 9"Hg Venturi, upgrading the Venturi would be the cheapest thing to do.

1691074651002.png
 
Will Kumley said:
... End goal for the panel is to ultimately have IFR capability with a GPS navigator, Comm that allows me to monitor a 2nd freq, maybe upgrade the transponder to incorporate the ADSB-out requirement into it. Currently ADSB is accomplished via a skybeacon wingtip light and it works well with the existing transponder.
Click to expand...
Less than a year ago I removed my mechanical AI & DG gyros, and the vac pump, replaced with uAvionix AV-30C, in my 172. They work well and the total cost (parts & labor) was about $6k.
The shop said the Garmin setup would cost about $9k total. That difference in price may be worth it if you want IFR capability. But since my 172 is VFR only, and always will be, I opted for the uAvionix.
 
Maybe off-topic/unsolicited, but look at the Garmin 375 or 355. LOTS of stuff in a small amount of panel space/weight. Better than a 175 for space-savings.
 
OneCharlieTango said:
Is that for a single G5? When I installed 2 of them, the shop said I could remove everything else.

Or maybe I misunderstood. *shrug*
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That's the entire beginning of that chapter. Given that the first bullet point mentions that you can install a maximum of two, I would think the next bullet points would apply regardless of single vs dual.

Maybe your plane is VFR-only?
Without your knowledge? :)
 
MRC01 said:
Less than a year ago I removed my mechanical AI & DG gyros, and the vac pump, replaced with uAvionix AV-30C, in my 172. They work well and the total cost (parts & labor) was about $6k.
The shop said the Garmin setup would cost about $9k total. That difference in price may be worth it if you want IFR capability. But since my 172 is VFR only, and always will be, I opted for the uAvionix.
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That price is actually better than I would expect. I'll have to see if the local prices are similar or if I'll have to pay the California and Covid tax. :)
 
OneCharlieTango said:
When I installed 2 of them, the shop said I could remove everything else.

Or maybe I misunderstood. *shrug*
asicer said:
Maybe your plane is VFR-only?
Without your knowledge? :)
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On a more serious note, looks like earlier versions of the install manual and AFMS did not have that limitation regarding the need to retain the rate-of-turn indicator.
 
asicer said:
That's the entire beginning of that chapter. Given that the first bullet point mentions that you can install a maximum of two, I would think the next bullet points would apply regardless of single vs dual.

Maybe your plane is VFR-only?
Without your knowledge? :)
Click to expand...
Just looked at the install manual, it definitely shows that a turn indicator is still required for IFR flight. Unless you specifically replace the turn indicator with a G5.
 
Will Kumley said:
Just looked at the install manual, it definitely shows that a turn indicator is still required for IFR flight. Unless you specifically replace the turn indicator with a G5.
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Yeah, please see my followup in post #27.
 
OneCharlieTango said:
In my experience, people who describe this sort of “light IFR” mission wind up being VFR only or getting themselves in serious trouble. If you aren’t starting out gung-ho for instrument flight, excited about breaking out at minimums after a couple of pleasant hours on top, maybe you should reconsider the IFR portion of your plan. It’s a lot of work to get the rating and, if you’re going to “use [it] minimally,” you’ll have a hard time keeping current and a very hard time staying proficient.
Click to expand...
The main reason for this description of light IFR is because I am unsure of how good of an IFR plane a Piper Colt would be. As a tube and fabric airplane I can't imagine it doing well if it encounters icing. There is no autopilot which I imagine is at the very least a huge advantage. I would maintain proficiency but my personal mins would be different than someone with a IFR 172 or 182.
 
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