AV30 and standard rate turns

[BiplaneCowgirl]

I'd like to upgrade my avionics with dual AV30s and replace my current turn coordinator with a second CDI for a new GPS. The AV30s can replace the attitude indicator and heading indicator and be primary slip indicator, but there is no rate of turn that I can find in it. So when my instrument instructor asks me to do a standard rate turn to the right (or whatever) I can be coordinated, but I can't see how to nail the rate of turn using the AV30. Any suggestions?

 

[asicer]

I'd like to upgrade my avionics with dual AV30s and replace my current turn coordinator with a second CDI for a new GPS. The AV30s can replace the attitude indicator and heading indicator and be primary slip indicator, but there is no rate of turn that I can find in it. So when my instrument instructor asks me to do a standard rate turn to the right (or whatever) I can be coordinated, but I can't see how to nail the rate of turn using the AV30. Any suggestions?

The install manual says you need to retain the turn coordinator. The DG acting as a reversionary backup AI is supplemental only.

 

[BiplaneCowgirl]

Thank you for the quick reply!! I couldn't find that anywhere. Buried in the installation manual is not too obvious.

 

[texasclouds]

Airspeed / 10 plus half that

100 kts / 10 = 10 + (10/2) = 15 degrees bank

maybe also an av-20 would satisfy the backup requirement.

 

[asicer]

maybe also an av-20 would satisfy the backup requirement.

Nope, AV-20 is NORSEE (Non-Required Safety Enhancing Equipment).

 

[Doug Reid]

Like Mark posted...IAS x 15 percent is standard rate.

 

[BiplaneCowgirl]

The rate of turn indicator is required for IFR. While the math is doable, I'll need the actual indicator in the panel. The AV30 doesn't do it. As far as I can tell the Garmin G4 and GI 275 don't do it either. Looks like I'll have to retain the old turn coordinator.

 

[Hang 4]

Both G5 and GI 275 can display a standard rate turn as well as slip indicator.

 

[Salty]

Both G5 and GI 275 can display a standard rate turn as well as slip indicator.

But they don’t allow for removal of the primary turn and bank or turn coordinator.

 

[luvflyin]

The rate of turn indicator is required for IFR. While the math is doable, I'll need the actual indicator in the panel. The AV30 doesn't do it. As far as I can tell the Garmin G4 and GI 275 don't do it either. Looks like I'll have to retain the old turn coordinator.

How much money do you want to dump into this? There are little rate of turn indicators. If you have space for a 2 incher, you could free up the 3 inch hole for a CDI. But then, I think there are 2 inch CDI’s also

 

[NordicDave]

Both G5 and GI 275 can display a standard rate turn as well as slip indicator.

But they don’t allow for removal of the primary turn and bank or turn coordinator.

2 GI-275’s do the trick. As the 275 is primary for all required indicators and with another 275 as back-up.

Frankly I never understood the FAA’s “logic” that one electric turn coordinator is OK, but one EFIS with battery back-up is not.

 

[NealRomeoGolf]

The rate of turn indicator is required for IFR. While the math is doable, I'll need the actual indicator in the panel. The AV30 doesn't do it. As far as I can tell the Garmin G4 and GI 275 don't do it either. Looks like I'll have to retain the old turn coordinator.

My plane is IFR legal and doesn't have a rate of turn indicator. That gets into electronic attitude backups and AC 91-75.

 

[Salty]

My plane is IFR legal and doesn't have a rate of turn indicator. That gets into electronic attitude backups and AC 91-75.

91.205

(3) Gyroscopic rate-of-turn indicator, except on the following aircraft:

(i) Airplanes with a third attitude instrument system usable through flight attitudes of 360 degrees of pitch and roll and installed in accordance with the instrument requirements prescribed in § 121.305(j) of this chapter

 

[texasclouds]

Backup AI mo betta than a TC, but cost mo munny. Might keep u mo alive tho.

 

[David Hempy]

AV-30 now (late 2025) shows standard rate turns. With an OAT, it has a marker on the angle indicator where std rate turn is, computed from TAS. Without an OAT, it has a trend indicator with a 3-degree/second mark.

Either one will get you the correct rate.

You'll need to update to v3.0.1 or better for this feature: https://uavionix.com/service-bullet...jeT_4L1lYyeFbMvbtlCLc5Qkk9a5_YDHwx8PK-72W2mEE

See it in action:

 

[Steamflyer]

Isn’t there an AC allowing removal of TC for an AI, suggesting two AIs is better than one with a TC? In any case sounds like it’s moot now since AV-30 apparently now does it.

Most of our planes cruise slowly and at one speed so just calculating the bank angle for standard rate should be more than enough for real life.

 

[Ed Haywood]

Isn’t there an AC allowing removal of TC for an AI, suggesting two AIs is better than one with a TC? In any case sounds like it’s moot now since AV-30 apparently now does it.

Most of our planes cruise slowly and at one speed so just calculating the bank angle for standard rate should be more than enough for real life.

Depends on whether you are talking VFR or IFR.

For VFR operations, an AI or TC is not required. If you have an optional TC or mechanical AI, there is an AC that authorizes replacement by a modern AHI.

For IFR, it is a bit trickier. The STC for the AV-30 is currently written as a replacement for an AI or DG, not as an EFIS. If you wanted to replace multiple instruments, you would need to use a different installation path than the STC. That would probably be painful.

That said, uAvionix is very active in updating their device capabilities and approvals. They just recently released the AV-HSI adapter, which allows the AV-30 to function as an HSI or CDI. So I would closely review the STC on a periodic basis for changes.

AV-30 now (late 2025) shows standard rate turns. With an OAT, it has a marker on the angle indicator where std rate turn is, computed from TAS. Without an OAT, it has a trend indicator with a 3-degree/second mark.

If you have an OAT, you can choose either the rate indicator or bank indicator in the setup menu. IMO the bank angle indicator is challenging to fly. At Oshkosh I spoke to their product manager and suggested they have an option to display both.

 

[AV8R_87]

For IFR, it is a bit trickier. The STC for the AV-30 is currently written as a replacement for an AI or DG, not as an EFIS.

There are two ACs in play. One that allows the replacement of the TC with a second attitude indicator, which must be electric.
The second AC allows the replacement of the mechanical attitude indicator with an electronic one, provided it has a back-up power source. Both ACs allow for these mods to be signed off as minor alterations.
Combine them and you have a path from a mechanical TC to the AV-30 as a minor alteration. Yes, you still must retain all other 6-pack instruments.

 

[Ed Haywood]

There are two ACs in play. One that allows the replacement of the TC with a second attitude indicator, which must be electric.

AC 91-75 excludes aircraft with a TC as required equipment for IFR flight.

 

[AV8R_87]

AC 91-75 excludes aircraft with a TC as required equipment for IFR flight.

I think I know what section of the AC you're looking at, but I don't agree with your interpretation.

 

[Ed Haywood]

I think I know what section of the AC you're looking at, but I don't agree with your interpretation.

Ok, I think you are correct.

However, to the point of the thread, two AV-30's installed as AI and DG/HSI would not allow the removal of the TC, even though the AV-30 now displays rate of turn. A third AV-30 would be necessary for IFR.

 

[MackMooney]

I'd like to upgrade my avionics with dual AV30s and replace my current turn coordinator with a second CDI for a new GPS. The AV30s can replace the attitude indicator and heading indicator and be primary slip indicator, but there is no rate of turn that I can find in it. So when my instrument instructor asks me to do a standard rate turn to the right (or whatever) I can be coordinated, but I can't see how to nail the rate of turn using the AV30. Any suggestions?

can you install it as a backup AI?

i'm planning to replace my TC with a backup AI mostly due to replacing my vacuum driven autopilot of which the TC was part of.

 

[AV8R_87]

However, to the point of the thread, two AV-30's installed as AI and DG/HSI would not allow the removal of the TC, even though the AV-30 now displays rate of turn. A third AV-30 would be necessary for IFR.

Agree. The STC only allows the replacement of the primary function (AI or DG).

 

[Steamflyer]

AC 91-75 indicates that one can replace the TB/TC with an independently powered AI in addition to the primary AI. Other than the reference to 91-205 (d)(3)(i), it really doesn't differentiate VFR from IFR. IFR itself requires only an AI and a TC as the second gyro instrument (and a DG of course). Surely one would be safer with an AI and another AI (independently power, say one vacuum and one electric with battery backup) an no TC at all than an AI, a TC, and a DG.

AC91-75 seems to acknowledge that this is ok for IFR (two independent AIs, no TC) as it is restricted to aircraft < 12,500 pounds and Part 23 or earlier. The AC even states that in this day and age (2003) an instrument which allows for determination of a standard rate turn (determination) is much less useful than an instrument which presents pitch and bank together. Reading between the lines, and including the FAA's preamble in the doc, suggests they'd rather have two AIs and no TC than one AI and a TC. The whole "third" AI language from 91-205 (d)(3)(i) seems to be have run roughshod over, and for good safety reasons.

 

[Ed Haywood]

Other than the reference to 91-205 (d)(3)(i), it really doesn't differentiate VFR from IFR.

AC 91-75 is only relevant to IFR.

"The purpose of this advisory circular (AC) is to provide a method to substitute an approved attitude indicator for the rate-of-turn indicator mandated by ... 91.205(d)(3)."

 

[Steamflyer]

AC 91-75 is only relevant to IFR.

"The purpose of this advisory circular (AC) is to provide a method to substitute an approved attitude indicator for the rate-of-turn indicator mandated by ... 91.205(d)(3)."

A much better summary of my thoughts. Hence always better to have two AIs than one AI and one TC if flying in IMC.

 

[midlifeflyer]

A much better summary of my thoughts. Hence always better to have two AIs than one AI and one TC if flying in IMC.

I don't know if this has been mentioned, but one of the reasons for retaining a TC is having a rate-based autopilot that relies on the external TC. That doesn't mean you wouldn't want a backup AI as well.

 

[Steamflyer]

I don't know if this has been mentioned, but one of the reasons for retaining a TC is having a rate-based autopilot that relies on the external TC. That doesn't mean you wouldn't want a backup AI as well.

That is true, and I believe that 91-75 or it's interpretation allows the preservation of such a TC even if it has now to be placed behind the panel or otherwise outside the scan (say on other side) for space reasons. Personally don't fly in IMC without a second pilot-side AI, which I tend to mount in a diagonal to the primary AI as it seems easier to corroborate than when placed next to the primary. YMMV.

 

[midlifeflyer]

That is true, and I believe that 91-75 or it's interpretation allows the preservation of such a TC even if it has now to be placed behind the panel or otherwise outside the scan (say on other side) for space reasons.

It's not an area in which I feel competent, but I think that the language in paragraph 5(b) suggests that so long as it's ok with the AP manufacturer it's OK with the FAA, subject to the usual "acceptable data" requirement.

 

[MauleSkinner]

Hence always better to have two AIs than one AI and one TC if flying in IMC.

Personally, I’d prefer the TC (actually a T&B) in light planes. But I was fairly thoroughly trained in needle-ball-and-airspeed, and am pretty comfortable with it.

 

[WDD]

Another POV for this old thread, but still important topic: Unless you just don't have the space, keep some of the old instruments including the electric gyro TC even if not required.

Just because you can doesn't mean it may be the best option. You can remove all six of your six pack and replace with something like twin GI 275's, which is what was done on one of our club's Skyhawks. Consensus is that we won't do it on the other Skyhawk. Why keep the old altimeter, TC, airspeed, VS? The extra back ups are good, club member like the six pack scan they are used to, and when a Safety Pilot or CFI is in the right seat, it's so much easier for him/her to see the instruments vs the smaller, more compact information display of the GI 275. And aesthetically, it just looks better IMHO.

In addition, by removing the AI and DG you'll already have the bulk of the "simplification benefit" by not having vacuum system. Not as much gained additionally by removing the others, less bang for the buck.

If you're replacing all with a glass panel like a G3x, that's a different story.