AP panel but only for trim?

[jandetlefsen]

Can the AP panel be used for trim only, without having AP servos installed? I plan to do my install in stages and the AP servos will only come in the last step. Plan was to install the AP penal early as a panel placeholder but now i'm reading about the trim functions that would save me from installing some of the Ray Allen relays. I also have the EMS so i don't even need the LED bar from Ray Allen

 

[Marc_J._Zeitlin]

Can the AP panel be used for trim only, without having AP servos installed? I plan to do my install in stages and the AP servos will only come in the last step. Plan was to install the AP penal early as a panel placeholder but now i'm reading about the trim functions that would save me from installing some of the Ray Allen relays. I also have the EMS so i don't even need the LED bar from Ray Allen

Sure. I have a power switch for my servos (I turn them off for takeoff and landing), so they're not on, powered, or talking on the bus. The trim system through the A/P controller panel works fine.

 

[jandetlefsen]

Sure. I have a power switch for my servos (I turn them off for takeoff and landing), so they're not on, powered, or talking on the bus. The trim system through the A/P controller panel works fine.

That's interesting thanks. Also some food for thought to switch off the whole AP for takeoff and landing.

 

[Marc_J._Zeitlin]

That's interesting thanks. Also some food for thought to switch off the whole AP for takeoff and landing.

I've never had the A/P go nuts on me (ever, in about 15 years or so between the D10A and the Skyview HDX), but still - it only needs to happen once, and you're always hand flying the takeoffs and landings anyway.

 

[cbretana]

Marc,

I found your concern about the A/P intriguing. Might I ask, in your opinion, do you not trust that you can override the servos in that situation?

I did have an incident about two years ago, right after I first installed the autopilot, that might be relevant. I had installed an A/P disconnect/CWS switch on my sidestick, as a pinky momentary toggle switch, (similar to what I had in the F-4). I installed it on the shaft of the sidestick, with the top of the toggle lever just below where my pinky would normally rest on the stick. Initially, it was a little bit too high, and before I moved it, I inadvertently activated it with my pinky without realizing it. Once this happened on final approach, about a mile or so out.
As I'm sure you know, (with the Hold to Engage set on), if the Dynon A/P is not engaged, toggling the disconnect switch (for 2 secs), causes it to engage, in roll mode. When this happened, although it was an adrenaline rush as I did not immediately realize what was happening, it was not hard to overpower the servos and maintain control. It was only after I was safely turning off the runway and it happened again that I realized what had happened and resolved to move the switch to a lower position on the sidestick.

 

[Marc_J._Zeitlin]

Marc,

I found your concern about the A/P intriguing. Might I ask, in your opinion, do you not trust that you can override the servos in that situation?

I do trust that I can override them, and the torque limit of the servos is set so that can be accomplished while never slipping during normal use (and I can always break the shear screw, if it comes to that). But the last thing anyone needs, as you found out, is to have someone/something grabbing the stick/yoke while you're trying to take off or land and putting a different pressure on it than you want or expect.

As you indicated you can turn the "Hold to Engage" capability off, so that you can't turn the A/P on by holding the button for a few seconds, if you want to. Then the inadvertent "turn-on" can be avoided, if the button is in a position that can be accidentally activated.

 

[cbretana]

Marc,

Yes, it was definitely not something i want to repeat. And I was in VMC when it occurred. I can imagine a very different outcome if it had happened when IMC on an approach...