GRT Avionics

Ok, now to decode the subject line....

I am considering the purchase of the GRT A/P servos because I understand the GRT system I have (the old WS H1 screens) will do GPSS steering.

The question is, assuming I want to 100% follow an IFR procedure (including proc turns) from the 430W, do I ALSO need to add the ARINC box such that I get ARINC signal from the 430W into the H1 and not just RS232 as I have it wired today.

Yes.

A man of few words. Thanks Bob!

Actually I am surprised you can set the OBS (either VOR or GPS) without an ARINC link.

Bob,
Your concern is founded. I cannot do any OBS feedback functions from H1 to 430W. When I initially wired the systems, budget was tight and I chose to write off any VOR functionality (meaning the OBS communication) . I used the direct outputs from the 430W to feed the H1s so I could get LOC and ILS.

This has worked just as advertised and is adequate for IFR useage.

However, over the last 18 months of flying, I have learned more about IFR GPS usage (My IFR ticket was done with full on steam) and what I am missing without the ARINC comunications. Now I see there is more to it that can make the navigation task easier (more than just VOR).

There is a growing list of changes in my panel/electrical system that is likely to be executed at next annual. The ARINC, ADS-B and GRT Servos (replacing TT Digi IIVS).

You could look at upgrading your TT to the VSGV model. Then, with the source switch on 430 (and arinc wiring going from 430 thru the switch to the TT) it should follow all the 430's commands, including holding patterns. You would need to switch back to the efis for ILS approaches, of course. But you really should get the arinc converter. VORs still make a good back up to gps. It seems a shame to have everything you need except the arinc so you can dial in OBS settings. And, I would have to read the fine print in the installation manual, but I suspect that it is a technical violation of the TSO to not have OBS capability on the 430 (e.g., technically it may not be legal for ifr use).
I have instructed someone with the older GRT screens which do not offer split screens. For VOR use I recommend you be prepared to go without engine instruments for a few seconds, change screen #2 to the HSI page, set the OBS, then go back to engine instruments. The CDI will display on the primary screen, just like the ILS does now.

It comes down to $$ again. I plan to sell the Trutrack which should provide plenty of cash to purchase the GRT servos and the ARINC box. Therefore the GPSS upgrade is free.

Interesting point about the 430W approved IFR installation Re VOR. Even though I have read considerably on it, I could have missed a statement demanding VOR presence. It will be moot soon. There is enough evidence of pilot creature comfort to make we want to do the change.

Sorry Bill I was not clear.It is now legal to use a TSO 145 or 146 (WAAS) GPS for IFR without VOR backup. But I am not sure if it is a legal gps installation without the GPS OBS function. You need to look in the 430W installation manual and see if it requires a working OBS input for an ifr installation.
You don't use the obs function often, but it is handy for off-route holding patterns.

According to the manual,
Minimum install for IFR includes a CDI, not specifically resolver feedback thru ARINC.
I do have CDI via the H1

Later in the manual it states that resolver feedback is preferred but not required.

Be that as it may, I recently saw a demo that makes me a believer in your point.

I was searching for something on Youtube and saw (in a 430W demo) what I "THINK" was an OBS turnable radial from whatever is the upcoming fix, whether it is a VOR or airport or intersection...whatever. If that is the "real" GPS OBS function, then that is entirely cool, I want it, and look forward to the ARINC upgrade.

Yes, that is most likely what you saw. Pushing OBS locks the waypoint, the gps will not automatically sequence to the next waypoint, even if you fly past it. And it will act just like a VOR centered at that waypoint, you will get to and from indications just like a VOR. And the selected radial and its reciprocal will show on the moving map display.