diamondaviators.net

mfdutra wrote: ↑Tue Feb 07, 2023 5:57 am I’d probably bet with anyone it’s just lawyer bullshit, in case someone lands with the YD on and destroys the airplane.

Perhaps so, but they already covered that scenario with an earlier limitation on AP/YD use during take-off, landing, and OEI operation.

If they really wanted to make it impossible to enable the YD without the AP and vice-versa, then they should've disconnected the YD button on the panel.

I wonder if it's just a poorly-worded restriction where they meant to say "don't use the AP without the YD," but only Diamond can speak to the intent and provide any reasoning behind it. Until then I guess we're stuck with it as a limitation.

I inadvertantly landed with the YD engaged once during ME training, and it was not fun. I don't remember the sequence that got me into that state, but I make sure to check for it now.

photoSteveZ wrote: ↑Tue Feb 07, 2023 2:43 am

Boatguy wrote: ↑Mon Feb 06, 2023 3:20 am I think Steve said that YD could not be engaged without also engaging "the rest of the AP", i.e., some vertical and lateral mode also active at the same time. I think the discussion was about having only YD active, with no other lateral or vertical mode active.

What I was trying to say is that it is possible to engage the YD without any other AP mode armed or engaged. I've landed with the YD engaged, without that being my intention. One of the methods you can use to disconnect the AP leaves YD engaged, and I suspect that it's the electric pitch trim. But, again, I haven't gone out to the airplane to confirm it.

You're correct; pushing the electric trim buttons will disconnect AP but leave YD engaged. You need to either push the red button or manually turn off the YD after this.

mfdutra wrote: ↑Thu Feb 02, 2023 1:23 am Please don't ever land with the YD on. That's a recipe for a landing accident. You WILL lose aircraft control on the ground if there is a crosswind.

This shouldn't be possible, but the Garmin manual is ambiguous. Does the AP disconnect button disconnect the AP and YD, or just the AP, and a separate push is required to disable the YD? Or, since my habit is to double click the disconnect button to also silence the warning, would that disconnect both AP and YD? What's the behavior if you disengage the AP by using the electric trim?

There is also a potential trap in that the pre-departure AFCS check calls for engaging the AP (which also engages the YD), then disengaging with the AP disconnect button. If the AP disconnect button does not disengage the YD, it will be engaged during the takeoff. And as Jon points out, if you use the electric trim button to end the AFCS check, the YD will still be engaged.

And I suppose if you manually turned on the YD (which Ed points out is prohibited, but can still be done), and never used the AP during the flight, so you didn't ever disconnect the AP, the YD would still be engaged.

It's probably best to check this in the plane, on the ground, rather than rely on the manual.

Boatguy wrote: ↑Fri Feb 10, 2023 11:04 pmDoes the AP disconnect button disconnect the AP and YD, or just the AP, and a separate push is required to disable the YD?

Pushing the red button definitely disconnects both the AP and the YD (confirmed today in the DA42, and I can't imagine it would be any different in the DA62). You'd have to use one of the other methods (trim switch or panel button) to turn off the AP without turning off the YD.

If you disengage the AP by either hitting the trim switch or by pressing the AP button on the MFD, that YD remains engaged. You need to use to red button to disengage all servos.

Cirrus had one or two total losses because of this, and they worked with Garmin to release a new software that automatically disengages the YD at 200 feet AGL, if you forgot it on.

That would be a nice to have; add that to NXi phase MCMXCVII...

Press the red button, Luke.