Replacing Turn Coordinator... or not?

On the last three flights before annual my turn coordinator began sticking in a turn long after I'd leveled out (see pic below). Now I need to replace it or come up with some solution b/c when the plane exits annual I'll be finishing up the IR training.

Currently I have a single Garmin G5 AI that has the turn coordinator built into it. The G5 says it's approved as the primary attitude indicator or turn coordinator. Probably a dumb question but it can serve as primary for both? All my experience is in steam gauge planes so I'm not confident in my interpretation of the regulations when you start having components capable of doing multiple things.

I like to minimize my single points of failure (e.g., relying on G5 for everything), but I also want to make sure I don't spend money needlessly. Any suggestions or recommendations on what to do here are welcome. I intend on doing a fair bit of IFR flying after getting the plane back and wrapping up IR so I want to make sure I'm well equipped (and legal, of course).

appendix A: TC behavior

 

I guess one of my questions was already addressed here.
Seems like a lengthy discussion about whether or not it can serve both purposes... Totally missed the thread before filing this one.

 

I had 2 G5 installed and my turn coordinator was grinding bad. I was told I had to have the turn coordinator. They got me a rebuilt midwest TC back in 2018. 964 hrs later it is working good still.

 

Gotcha. Curious how much was the rebuilt unit?
The shop is quoting me a new TC at $1575 + 1.5h labor. The advantage is that AircraftSpruce is down the street and they can pick it up in no time and get it installed. The drawback is... the price.

 

Trade it in for another with AQI for $500 or send it to them for overhaul for less than that.

 

I don't remember what it cost, I will have to look and I will post it here.

 

Thanks Gary, no need to pass along the cost. I'm asking my shop to help me get a quote from AQI on doing an exchange or OH my existing unit.
The 1750$ price tag for parts and labor on a new unit was more than I was expecting for that instrument.

 

I have an Aspen and a backup vacuum AI. Then my TC failed. I know if I needed the space for something else, I’d be covered by the Aspen. But I like that redundancy with something I find customary and easy to use to check standard rate and the ball. Also, it didn’t require a lot of extra thought on the matter. The cost I do not remember, but I think it was around $700 for new in 2017. If I was doing it again, I might consider an AV30.

 

Do you have an autopilot, and if so, what drives it?

 

Nope. My autopilot was disconnected when I got my Garmin G5. Thankfully I rarely ever used it before hand anywho.

 

Curious about the logic of requiring a TC with dual G5's. I assume it is since TC serves as backup to AI for partial panel. But with dual G5's in reversionary mode, you already have backup. I guess you need a 3rd AHI to be redundant enough?

 

Believe the T/C can be replaced with another AI, or hidden if the AP requires it and no panel space. Much better solution IMHO for any airplane flown in IMC. The ball in the G5 ought to do, or maybe a simple stick on if seat-of-the-pants isn’t coordinating sufficiently.

An AV-30 is a nice second AI. I brand new electric turn coordinator is about $1600 from Mid-Continent for reference.

 

Believe can still remove TC and add any additional AI like another G5 or an Av-30.

see AC 91-75

 

TC is required for IFR ("GRABCARD" to annoy the mnemonics haters out there ). G5 is only primary for AI and HSI while the rest of the functions (altitude, airspeed, etc) are only advisory.

 

The advisory circular goes into detail as to how a turn coordinator is a poor substitute for a failed AI when flying by instruments and therefore a second AI is preferable even at the expense of losing the TC.

I.e. when push comes to shove, a pilot is more likely to diagnose a failing/failed AI and then be more able to fly with a second AI than with a TC, airspeed, and heading (partial panel).

 

Right, but the FAA doesn't seem to consider the HSI's reversionary mode as a second AI. I'm guessing either the FAA doesn't have confidence in the G5's reversionary feature or they're trying to fit real life into the rules rather than the other way around (Hanlon's Razor, and all that).

 

Call these guys for an overhaul NuTek

http://nu-tekinc.com/index.php

 

I believe you are correct about that - a G5 that's not locked as an AI (i.e., a single unit that is primarily an HSI but not locked to that function) does not count as primary AI and therefore it plus an AV-30 would not be sufficient. In one aircraft I have an AV-30, a G5 HSI, and did in fact then go and put in a TC for the second gyro source.

OP, however, seems to say his primary AI (presumably locked to that function) is a G5, in which case I believe that AC 91-75 indicates they can remove the TC in favor of a second AI. At least that's what the panel seems to show.

If I had OP's panel I'd put a second G5 as an HSI in place of the DG and be done with it.

 

If only they were. I would have swapped my TC out with one by now. Try almost $4,000 with tax.

Cheapest electric AI out there is the RCA 2610 and it's almost 3K. Nothing under **2.5K that's electric. **This is for AIs that don't require extra labor of plumbing into the pitot-static (your AV-30s, G5s et al) and/or D9/15 pinout on top of it, labor which negates the price savings over the $4K 2/4 pin cannon-plug (already existing behind the TC being removed) in the first place.

I'd still be inclined to go electronic though if I ever pull the trigger on replacing the TC. The mechanical ones found on ebay from the usual rando on there are probably shot anyways, and would require overhaul $ just to bring back to usable form. Not worth the discount.

I have the same plane as the OP. Had I gone through with a G5 installation like he did, I wouldn't have got rid of the vacuum AI, which is one of the two instruments (the DG is also an input device for the century OEM autopilot in the arrows) that powers the AP. It would be an easy move to just put the vacuum AI where the TC sits, and gain two AIs with no autopilot loss.

 

Electric Turn coordinator is actually < $1400.
https://www.aircraftspruce.com/catalog/inpages/tcbmodel_10-01024.php

IMHO replace broken TC with AV-30. ~$2300. Have installed several under IA supervision and it's not very hard at all. If just an AI it takes power and ground, in addition to pitot and static line splice-ins. Recommend at also at least running pins 8 and 15 out for serial hardware update, though think they are going to have a wireless dongle for that soon. For IFR should have a re-cert since pitot-static modified.

Overall prefer to have two AIs in a plane flown IFR/IMC "regardless" of cost.

 

In general, a turn coordinator is down on the list a ways, for $$ priority. You can just use the rudder by ‘feel’ for phase of flight. Yes, an overhaul/ exchange is a lower cost option.

 

Oops, reading comprehension fail on my part, I just re-read and you indeed were talking about a new TC, not AI.

 

Exactly right. I also have a Century 2B (Piper Autocontrol 3B). While I have an Aspen, there exists an option for the Aspen AI to drive this legacy autopilot (the G5 does not have that capability at all) by paying $2500(?) for an EA100(?). However, the Aspen HSI comes standard with that autopilot interface(as does the G5). It was cheaper and easier to retain the vacuum AI that was already driving the autopilot. It also serves as the backup AI required by STC for the Aspen to be an EIS, which is important for safety anyway. That is why, when my TC died, it made less sense for me to put in a 3rd AI in that spot, although one gets additional goodies with the AV30, like Angle Of Attack.
My plan however is when an if the AV30 enables its promised ability to be an AI data source for my autopilot, I could then remove the vacuum system and vacuum AI.
But getting back to the TC, I actually like having 3 disparate sources of complimentary data to cross check for IFR operations.

 

My understanding is that for those wishing to keep the interface to a legacy attitude-base AP (Century and King in particular), the GI275 is supplanting the G5 as the go-to indicator. It also mounts easily into a 3.125" hole, though it is also much deeper than the G5 which is a consideration in some panels.

A pair of 275s may obviate the vacuum system; if the revisionary capabilities are not enough in the pilot's mind to ensure a working AI no matter what, an AV-30 in place of the TC complements a "round hole" system nicely.

All this is many AMUs, but think about how you'd feel about flying at night in IMC partial panel. It's doable but requires a level of proficiency that many GA pilots cannot maintain.

 

Yep. Just did one last week. People make out D subs and pitot static like it's some dark art. 9 pin D sub with 5 wires takes 15-30 minutes to build. And the push-to-connect PTC ports on the AV-30 rock. I got PTC-MPT adapters for the rest of my instruments, a 6 port manifold, and some 1/4 polyurethane tubing and replaced the entire pitot-static system in less than an hour. Way better than the 40 year old rubber and vinyl with barbed fittings that came out. And a zillion times easier to work on than aluminum tubing and brass fittings.

 

Well, legit shout out to this thread for pushing me over the hump on a topic I'm generally very antagonistic towards (avionics in facbuilt installations).

Did some additional digging online and was able to find a used electric mechanical AI with a recent overhaul for a capex i could stomach (sub 2amu), and replace my otherwise perfectly working TC with.

My sincere belief in that AC's argued safety thesis is in the end, stronger than my visceral disdain for facbuilt pricing hackery. Thanks again for the thread OP, and everybody stay safe out there.

 

Great outcome! A second AI always trumps a TC IMHO.