G3X autopilot power switch

bobmarkert · #1 06-20-2013, 04:48 AM

I've just spent 2 1/2 hours in the G3X pilot guide and install manual. You guys packed such a phenomenal amount of capability in the G3X that I almost giggle out loud like a school-girls every time I read the manuals (shields up).
I have two questions:

1) I had some engraving done for my panel prior to the release of the new LRUs. I was going to use a second party autopilot and have provided for an autopilot power switch (on-off). I am now installing the new G3X products so will I not have a separate autopilot. Is there any need for an autopilot on-off switch for the G3X autopilot?

2) Page 121 of the Pilots user guide discusses frequency auto tuning with an SL40 radio used as an example. Will the G3X autotune the GTN 650 frequencies (NAV and COMM)?

ColoRv · #2 06-20-2013, 05:13 AM

My opinion only here, but the ability to turn power to the servos off seems like a safety issue in case of some sort of runaway or autopilot disconnect failure.

I'm hoping to hear I am wrong on this, but I believe you'll find the g3x will not auto tune the GTN....something about experimental controlling certified. It seems wrong not to allow two Garmin products to work together to me, but according to the expert I spoke to (that guy who is only happy if we are broke), it has to do with the FAA and certified blah blah blah. I hope I misunderstood...which is certainly possible.

What I was told was the GTN is such a joy to use...we won't mind touching its screen once in a while. Mine shows up today!!! It's Christmas!

Cue team X.....

Brantel · #3 06-20-2013, 05:29 AM

It won't push freq's to the GTN but it will to SL30/SL40/ICom A210/Others that use the SL30 protocol/Most likely the GNC/GTR series.

This is not an oversight, it is that way on purpose I am told.

The good news is that the GTN is so easy to use, it makes it a non issue.

g3xpert · #4 06-20-2013, 05:36 AM

Hello Bob, thanks for your questions. There is no requirement to put in a power switch for the GSA 28 servos, but it can't hurt to do so. I personally like to see a pullable circuit breaker or switched power input to whatever kind of autopilot I'm flying with; old habits die hard. Under normal circumstances I think you would probably want to leave the autopilot power switched on all the time, and use the switch as a backup to the backup to the various other safety features already present.

As for sending comm frequencies to a GTN via RS-232, the previous posters are correct, this is not supported by the GTN. But as Brian pointed out, the GTN does have its own user interface for selecting comm frequencies.

- Matt

Captain_John · #5 06-20-2013, 05:42 AM

Bob,

I am noodling over the AP witch issue too.

I agree that the AP should have a physical, pilot controlled means of disconnect in the event of a servo malfunction... just like certified planes always do.

I am planning for fuses with my install.

My inclination right now is to install a fuseholder in the panel adjacent to the 305 controller to do this. It may become a switch or even a pullable circuit breaker before it is done.

My two...

CJ

Captain_John · #6 06-20-2013, 05:43 AM

Matt, I guess you beat me to the punch! ha!

Well, looks like I am on the right track anyways!

CJ

bobmarkert · #7 06-20-2013, 05:53 AM

I think there is info somewhere in a thread here that says to wire the infinity grip trim switch directly to the servos and then the servos would assume the role of relay and pass power to the Allen trim motors. That will eliminate the need for the trim relay board (which I already have but was not going to install). If the servos are de-powered with an A/P on-off Switch, does that mean the trim switch is passing the motor power through the switch (can the infinity trim switch handle that requirement?).
Bottom line questions:

1) do I still need a trim relay board with the new Garmin A/P servos, especially now that I will have a switch to de power the servos?

2) do I need/ should I have an on-off switch? ... Just answered above, I'll install it as planed (panel already engraved so I'm happy :-) )

P.S. I'm sitting in a B&B in Vernonia OR getting ready for day two of transition training with Mike Seager. The man is fun to fly with and has nerves of steel, no make that titanium!!!!!!!

I wish Gandolf was here, he'd know what to do.........although Matt rocks too!

Captain_John · #8 06-20-2013, 06:06 AM

Bob, can you direct me to a wiring diagram of the servos and trim stuff?

I am awaiting my G3X stuff now and don't have anything to read.

CJ

bobmarkert · #9 06-20-2013, 06:45 AM

Try these.

http://static.garmincdn.com/pumac/190-01115-01.pdf
http://static.garmincdn.com/pumac/19...-00_0K_Web.pdf

g3xpert · #10 06-20-2013, 06:48 AM

Quote:

Originally Posted by bobmarkert

do I still need a trim relay board with the new Garmin A/P servos, especially now that I will have a switch to de power the servos?

Bob,

If your airplane has a trim switch for the pilot only, you can wire it directly to the GSA 28 servo. The trim switch must obviously be capable of handling the current requirements of the trim motor. The GSA 28 has a fail-safe feature that connects the trim motor directly to the trim switch even if the autopilot servo itself is not receiving power.

If you have trim switches for both the pilot and copilot, then you will need an external third-party device (relay board, etc.) to combine the two trim switch inputs into one. The output from that device would then connect to the GSA 28 servo as above.

For further information on how the trim interface works, take a look at section 9.5.2.3, sections 9.10 through 9.13, section 9.16, and figures C-1.4 and C-1.5 in the G3X Installation Manual.

- Matt