Yaw Damper behavior

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photoSteveZ
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Yaw Damper behavior

Post by photoSteveZ »

mfdutra wrote: Sun Jan 29, 2023 12:48 am
You cannot use YD without the AP engaged, which is ridiculous. Minimum altitude select 1200 AGL, which makes it pretty much illegal to fly a circle approach on the AP (the level phase), which is the standard procedure in most serious flight schools.
There is a way to have the YD engaged without the rest of the AP. I've never done it 'on purpose', but I've seen a number of instances where the nose wheel has been incredibly hard to steer on the ground because the YD was still engaged.

I will have to go try it out in the airplane to give you the exact command sequence, but as I recall it involves engaging the autopilot with the AP button and then disengaging it with the pitch trim switch.
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Re: DA62 - the greatest GA aircraft ever built?

Post by mfdutra »

photoSteveZ wrote: Sun Jan 29, 2023 7:19 pm There is a way to have the YD engaged without the rest of the AP. I've never done it 'on purpose', but I've seen a number of instances where the nose wheel has been incredibly hard to steer on the ground because the YD was still engaged.
You can do that technically and it works, just like you can use altitude capture below 1200 AGL and it works. Somehow those two things are section 2 limitations in the POH, which is irritating. You can even use the AP OEI technically, although that's a bit questionable ADM.

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.
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Re: DA62 - the greatest GA aircraft ever built?

Post by photoSteveZ »

mfdutra wrote: Thu Feb 02, 2023 1:23 am
photoSteveZ wrote: Sun Jan 29, 2023 7:19 pm There is a way to have the YD engaged without the rest of the AP. I've never done it 'on purpose', but I've seen a number of instances where the nose wheel has been incredibly hard to steer on the ground because the YD was still engaged.
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.
A good addition to my personal landing checklist.
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Re: DA62 - the greatest GA aircraft ever built?

Post by Ed McDonald »

Not using the YD for take-off, landing and single engine flying is among other autopilot limitations.
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Re: DA62 - the greatest GA aircraft ever built?

Post by nworthin »

photoSteveZ wrote: Sun Jan 29, 2023 7:19 pm There is a way to have the YD engaged without the rest of the AP. I've never done it 'on purpose', but I've seen a number of instances where the nose wheel has been incredibly hard to steer on the ground because the YD was still engaged.

I will have to go try it out in the airplane to give you the exact command sequence, but as I recall it involves engaging the autopilot with the AP button and then disengaging it with the pitch trim switch.
I read this entry a few days ago, scratched my head, and then on my next flight took off with PIT and ROL modes selected and, after gaining some altitude, pressed the YD button and YD appeared on the scoreboard.

So, I’m confused that others seem to think there’s a “patting your head and rubbing your belly” secret handshake requirement to engage the yaw damper without AP on.

I agree it’s important to understand when you would want to use it but it seems like you basically can turn it on whenever….

What am I missing?
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Re: DA62 - the greatest GA aircraft ever built?

Post by Boatguy »

nworthin wrote: Mon Feb 06, 2023 2:31 am
photoSteveZ wrote: Sun Jan 29, 2023 7:19 pm There is a way to have the YD engaged without the rest of the AP. I've never done it 'on purpose', but I've seen a number of instances where the nose wheel has been incredibly hard to steer on the ground because the YD was still engaged.

I will have to go try it out in the airplane to give you the exact command sequence, but as I recall it involves engaging the autopilot with the AP button and then disengaging it with the pitch trim switch.
I read this entry a few days ago, scratched my head, and then on my next flight took off with PIT and ROL modes selected and, after gaining some altitude, pressed the YD button and YD appeared on the scoreboard.

So, I’m confused that others seem to think there’s a “patting your head and rubbing your belly” secret handshake requirement to engage the yaw damper without AP on.

I agree it’s important to understand when you would want to use it but it seems like you basically can turn it on whenever….

What am I missing?
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.

AP modes can be selected without turning on the AP. I usually take off with HDG (runway or ATC specified) and FLC with assigned altitude and standard cruise climb speed.

You took off with PIT/ROL selected, but the AP off, correct? Then you punched YD and it showed up, but the AP was still off, correct? When did you turn on the AP?
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Ed McDonald
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Re: DA62 - the greatest GA aircraft ever built?

Post by Ed McDonald »

The yaw damper is an integral part of the autopilot system and must not be used separately. (AFM Page 2-43).
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Re: DA62 - the greatest GA aircraft ever built?

Post by CFIDave »

Just to provide a different perspective, single-engine turboprop pilots are taught to turn on the yaw damper (but not autopilot) almost immediately after rotation (i.e., right after raising the gear and flaps). Hitting the GFC700's YD button is the fastest way to take out the extensive right rudder trim configured before takeoff. Right rudder trim is essential to countering extensive turboprop torque during the takeoff roll.

The DA62 is different because its left-turning tendencies during takeoff are easily manageable using just rudder, without having to also crank in right rudder trim with the round knob. The DA62's rudder trim is manual (not electric), and operates independently from the GFC700's yaw damper that also controls rudder.

However there is some interaction between the two rudder-controlling systems: The DA62's GFC700 will display a left or right arrow in the PFD's "scoreboard" if too much manual rudder trim has been applied -- more than the yaw damper can compensate for -- thus encouraging the pilot to reduce manual rudder trim.
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Re: DA62 - the greatest GA aircraft ever built?

Post by photoSteveZ »

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.
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Re: DA62 - the greatest GA aircraft ever built?

Post by mfdutra »

The YD servo will arm and it works by itself. That’s pretty standard business on most airplanes. Somehow, Diamond made that illegal in the section 2 of the POH. I’d probably bet with anyone it’s just lawyer bullshit, in case someone lands with the YD on and destroys the airplane.
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