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  #1  
Old 02-03-2018, 12:26 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
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Default Autopilot Switch

I put an autopilot switch on my panel to turn it on and off. Would it be best to switch the servos off with the switch, or the Garmin GMC307? Both also have CB I can pull if needed. I think if the 307 is off the servos will not run...... But will it throw G3X alarms? If I switch the servo power and turn that off does the G3X complain then? What's best....
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  #2  
Old 02-03-2018, 02:34 PM
Tom023 Tom023 is offline
 
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I'm having Stein build my panel and had this conversation with him. My AP switch will cut servo power.
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  #3  
Old 02-03-2018, 02:40 PM
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Checkmate Checkmate is offline
 
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Default Plus 1

Quote:
Originally Posted by Tom023 View Post
I'm having Stein build my panel and had this conversation with him. My AP switch will cut servo power.
Same here, switch will cut servo power.
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  #4  
Old 02-03-2018, 04:22 PM
KeithB KeithB is offline
 
Join Date: Mar 2014
Location: Granbury, TX
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As the autopilot actually resides in the G3X, and I have a switchable CB on the circuit that powers the AP servos, I eliminated an AP switch. My flying practice is to have the AP available at all times (blue button at the least) so I only needed power control for resets or an emergency. Both the servos and GMC 307 are on the main bus.
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  #5  
Old 02-03-2018, 05:25 PM
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czechsix czechsix is offline
 
Join Date: Mar 2006
Location: Spring Hill, KS
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In my RV-8A I always used the AP button on the GMC or the red button on the stick to engage/ disengage the autopilot. I also had a toggle switch that could shut off servo power, but it was there mainly as a backup/safeguard and I never needed to use it in flight. I think it's a good idea to have a convenient means of turning off power to individual boxes regardless of their function, whether it be done by CBs or toggle switches (a fuse can also be pulled but is generally more difficult to quickly find and remove the correct one, and harder to restore power again if desired).
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  #6  
Old 02-03-2018, 11:54 PM
TASEsq TASEsq is offline
 
Join Date: Aug 2017
Location: Melbourne, Australia
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In larger (certified) aircraft this is called TCS - touch control steering.

Basically the servos (or clutch etc) is disconnected so that you can temporarily maneuver the aircraft while holding the switch, but the ap remains active and trying to steer the aircraft. You let go of the button and the ap will return the aircraft back to where you had it. Good for traffic events or weather avoidance, or any other time you want to temporarily maneuver without taking all the ap modes off and having to reselct them all on again. Usually TCS is a momentary action switch.

Most have a seperate switch which cuts power to everything, in case if servo runaway etc. (ga certified sometimes have this or you just red collar the CB so you can find it in a hurry).

Seems both may be useful in an IFR machine.
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  #7  
Old 02-04-2018, 11:04 AM
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czechsix czechsix is offline
 
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Quote:
Originally Posted by TASEsq View Post
In larger (certified) aircraft this is called TCS - touch control steering.

Basically the servos (or clutch etc) is disconnected so that you can temporarily maneuver the aircraft while holding the switch, but the ap remains active and trying to steer the aircraft. You let go of the button and the ap will return the aircraft back to where you had it. Good for traffic events or weather avoidance, or any other time you want to temporarily maneuver without taking all the ap modes off and having to reselct them all on again. Usually TCS is a momentary action switch.
In the Garmin G3X autopilot what you are describing as TCS is called CWS (Control Wheel Steering). It is accomplished using the same momentary pushbutton as the AP Disconnect (usually red and located on the control stick). A quick jab will disconnect the autopilot. If you push and hold it instead, it disconnects the servo clutches but the autopilot modes stay active. You can then hand fly the airplane as desired (around a cloud or flock of birds for example). When you release the button the servo clutches re-engage and the autopilot continues flying. In some modes such as Heading or Nav, the autopilot will return to tracking the heading bug or nav reference. In other modes such as Pitch/Roll, VS, and IAS the reference will synch to the current value upon releasing the button. So for example if you were climbing in VS mode at 300 FPM, and you hold down the CWS button and pull the nose up to increase climb rate to 500 FPM and then release, the autopilot will now be using 500 FPM as the new reference to hold. All of this is documented in the G3X Pilot's Guide BTW...
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