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Question about Garmin Autopilot power redundancy

K

kirkbauer

Active Member
There are several portions of the Garmin G3X Touch suite that allow for redundant power inputs -- the GDU 460 display, for example. The GMC 507 Autopilot Controller also has redundant power inputs.

But I don't see that the GSA28 servos have redundant power inputs. Am I missing something?

I'm considering using two separate electrical busses in my RV-10 that's under construction, and I'm curious if you can connect the autopilot system so that it can fully work using either bus. Right now it seems like that would only be possible with an external set of diodes. But, if that's true, I'm curious why the GMC 507 has redundant power.
 
An AP should not be considered critical to flight. That is most likely why Garmin does not provide redundancy on the servo power.

The GMC also controls the FD and bugs which are very useful in flight when the crap hits the fan.

You can use a set of diodes but make sure you consider power rating and what the voltage drop is going to do to your circuit when selecting the diodes. Also put them as close to the servo as possible.
 
I have a semi-related question. What's the best way to kill the autopilot system in flight just in case something goes haywire?

1) I understand that a long hold of the AP Disconnect switch should shut everything down... right?
2) Or is it best to put the AP servos on circuit breakers?
3) What about disabling ESP? For a non-aerobatic airplane (RV-10) is it necessary to have a switch to disable that just in case? Or will options 1 and/or 2 suffice?

I read this thread and that got me thinking: https://vansairforce.net/threads/g3x-esp-learning-experience.178063/
 
kirkbauer said:
I have a semi-related question. What's the best way to kill the autopilot system in flight just in case something goes haywire?

1) I understand that a long hold of the AP Disconnect switch should shut everything down... right?
2) Or is it best to put the AP servos on circuit breakers?
3) What about disabling ESP? For a non-aerobatic airplane (RV-10) is it necessary to have a switch to disable that just in case? Or will options 1 and/or 2 suffice?

I read this thread and that got me thinking: https://vansairforce.net/threads/g3x-esp-learning-experience.178063/
Click to expand...
My understanding - which comes from a certified installation of a G503 run by G275 mini efis units - is that holding down the yoke (stick) operated disconnect button disconnects everything only as long as the button is held down. When released, ESP re-engages. Manual suggests that, in an emergency, stick button be held continuously down until the ESP is disengaged, either thru the efis menu or by pulling the AP CB.
 
BobTurner said:
My understanding - which comes from a certified installation of a G503 run by G275 mini efis units - is that holding down the yoke (stick) operated disconnect button disconnects everything only as long as the button is held down. When released, ESP re-engages. Manual suggests that, in an emergency, stick button be held continuously down until the ESP is disengaged, either thru the efis menu or by pulling the AP CB.
Click to expand...

That's great to know. So if I'm going to have a few circuit breakers, it sounds like it is good to have one for the autopilot.

If I have servos for pitch, roll, and yaw, does it make sense to have one breaker connected to all three servos?
 
kirkbauer said:
That's great to know. So if I'm going to have a few circuit breakers, it sounds like it is good to have one for the autopilot.

If I have servos for pitch, roll, and yaw, does it make sense to have one breaker connected to all three servos?
Click to expand...
Since I do not consider the autopilot to be a ‘safety of flight’ type of equipment, I just have one CB.
 
The ability to depower the autopilot quickly should be incorporated.
1. The autopilot is always armed in the background for ESP functions.
2. There are some failure modes that could keep the normal buttons from disengaging.
 
kirkbauer said:
I have a semi-related question. What's the best way to kill the autopilot system in flight just in case something goes haywire?

1) I understand that a long hold of the AP Disconnect switch should shut everything down... right?
2) Or is it best to put the AP servos on circuit breakers?
3) What about disabling ESP? For a non-aerobatic airplane (RV-10) is it necessary to have a switch to disable that just in case? Or will options 1 and/or 2 suffice?

I read this thread and that got me thinking: https://vansairforce.net/threads/g3x-esp-learning-experience.178063/
Click to expand...
1. A momentary press of the Autopilot disconnect button will disengage the autopilot.
Capture.PNG

2. You will find the main Autopilot interconnect drawing on page 24-9 of the G3X Installation Manual (Rev AU). On this page, you will see that each servo is powered by #22AWG wiring, protected by 3A circuit protection.

3. ESP can be armed/disarmed in the AFCS menu. A configuration setting determines if ESP Is armed or disarmed on each power up. The switch is an optional alternate method to inhibit ESP. It will remain inhibited for as long as the switch is active. When ESP is armed, and one or more of the defined ESP thresholds are crossed, it is possible to remove the servo torque being applied to the control surfaces by ESP, by pressing the AP Disconnect button, activating the remote switch if installed, or disarming ESP in the AFCS menu. When using the AP disconnect button, if the switch is released, servo torque will resume if the aircraft is still outside of the defined threshold. If the AP disconnect is pressed and held for more than 5 seconds, subsequent ESP driven servo torque will be inhibited, and the pilot will be notified by a CAS message. More information on Autopilot operation can be found in the G3X Touch Pilot's Guide, beginning on page 315. ESP information can be found beginning on page 307.
Capture.PNG
kirkbauer said:
That's great to know. So if I'm going to have a few circuit breakers, it sounds like it is good to have one for the autopilot.

If I have servos for pitch, roll, and yaw, does it make sense to have one breaker connected to all three servos?
Click to expand...
As mentioned above, see page 24-9 of the installation manual, as we provide specific guidance for this aspect of the installation.

Thanks,
Justin
 
g3xpert said:
If the AP disconnect is pressed and held for more than 5 seconds, subsequent ESP driven servo torque will be inhibited, and the pilot will be notified by a CAS message. More information on Autopilot operation can be found in the G3X Touch Pilot's Guide, beginning on page 315. ESP information can be found beginning on page 307.
Click to expand...

How does this interact with CWS if you have it enabled? With CWS enabled, a long press of the AP Disconnect button I assume just means you stay in CWS mode for a while. Does enabling CWS prevent the "hold for 5sec disables servo torque"?

I checked the G3X Touch Pilot's Guide and I see everything you were talking about but nothing about the "more than 5 seconds hold".
 
Holding for more than 5 sec disabling the servo is only when ESP has engaged due to an envelope excedance.
Under normal circumstances within the envelope (ESP not engaged) you can hold the disconnect button as long as you want to enable CWS. NOTE: This also disables trim.
 
kirkbauer said:
How does this interact with CWS if you have it enabled? With CWS enabled, a long press of the AP Disconnect button I assume just means you stay in CWS mode for a while. Does enabling CWS prevent the "hold for 5sec disables servo torque"?
Click to expand...
CWS is an autopilot function and only applies when the autopilot is engaged. ESP functions only when the autopilot is not engaged, so there is no interaction between these.
kirkbauer said:
I checked the G3X Touch Pilot's Guide and I see everything you were talking about but nothing about the "more than 5 seconds hold".
Click to expand...
Page 308 in revision Y.
 
g3xpert said:
1. A momentary press of the Autopilot disconnect button will disengage the autopilot.
View attachment 61207

2. You will find the main Autopilot interconnect drawing on page 24-9 of the G3X Installation Manual (Rev AU). On this page, you will see that each servo is powered by #22AWG wiring, protected by 3A circuit protection.

3. ESP can be armed/disarmed in the AFCS menu. A configuration setting determines if ESP Is armed or disarmed on each power up. The switch is an optional alternate method to inhibit ESP. It will remain inhibited for as long as the switch is active. When ESP is armed, and one or more of the defined ESP thresholds are crossed, it is possible to remove the servo torque being applied to the control surfaces by ESP, by pressing the AP Disconnect button, activating the remote switch if installed, or disarming ESP in the AFCS menu. When using the AP disconnect button, if the switch is released, servo torque will resume if the aircraft is still outside of the defined threshold. If the AP disconnect is pressed and held for more than 5 seconds, subsequent ESP driven servo torque will be inhibited, and the pilot will be notified by a CAS message. More information on Autopilot operation can be found in the G3X Touch Pilot's Guide, beginning on page 315. ESP information can be found beginning on page 307.
View attachment 61208

As mentioned above, see page 24-9 of the installation manual, as we provide specific guidance for this aspect of the installation.

Thanks,
Justin
Click to expand...
When ESP is disabled by holding AP disconnect for more than 5 seconds so a pilot can fly some acro, how is ESP turned back on most expeditiously? Does holding the AP disconnect on for more than 5 seconds again reenable ESP?
 
Lucmac said:
When ESP is disabled by holding AP disconnect for more than 5 seconds so a pilot can fly some acro, how is ESP turned back on most expeditiously? Does holding the AP disconnect on for more than 5 seconds again reenable ESP?
Click to expand...
This is also on page 308 of the pilot's guide (revision Y):

Enabling/disabling ESP using the G3X Touch Autopilot Interface:
1) From the PFD, touch the Autopilot Status Box. The Automatic Flight Control System page is displayed.
Or:
From the Main Menu, touch Flight Controls.
2) Touch the ESP button on the Automatic Flight Control System page to enable/disable ESP
Click to expand...
 
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