G1000 ESP question

[FlyingPenguin]

Hello all,

Has anyone tested their ESP minimum speed function on their G1000?

In reading the DA42 AFM, it states that once reaching the minimum speed of 90kts, the AFCS would cause the plane to pitch down and maintain 90, or 90kts plus 2kts, depending on the mode you are in.

So, naturally, I expected the plane to start pitching down shortly after hitting the 90 kts mark. I did a test, and surprisingly I was wrong. My plane held the altitude great at 2500, but never pitched down until it reached 76kts indicated!

Anyone try this and see the same thing?

[Soareyes]

I've tried to get my DA42 Nxi to demonstrate underspeed protection (USP) but without success. Makes me nervous to allow the plane to get that slow when I am not the one manipulating the controls.

And why is USP only active when the autopilot is engaged? I guess the most likely scenario is to avoid stalling while the autopilot is trying to climb in VS mode but what if I get distracted and stall while hand flying? I do get the yellow MINSPD caution below 90 kts while landing. Seems like USP should be always on unless the gear is down.

Roll mode/bank angle protection is always on even without the autopilot.

[FlyingPenguin]

I've tried to get my DA42 Nxi to demonstrate underspeed protection (USP) but without success. Makes me nervous to allow the plane to get that slow when I am not the one manipulating the controls.

And why is USP only active when the autopilot is engaged? I guess the most likely scenario is to avoid stalling while the autopilot is trying to climb in VS mode but what if I get distracted and stall while hand flying? I do get the yellow MINSPD caution below 90 kts while landing. Seems like USP should be always on unless the gear is down.

Roll mode/bank angle protection is always on even without the autopilot.

Yeah, the system letting it goto 76 Kts before pitching down is a bit too slow in my book. Tho, I did get warning flashing on the PFD and audio warning as well at 90 Kts. So, in reality, corrective input would have been made shortly after the warning. Where I see this USP come into play the most is during decent to a new altitude. At level off, one forgets to increase the power setting. Climb, I use FLC instead of VS mode to avoid the risk of stalling.

Hmm..the USP should deactivate when you are within 200 AGL. Are you going <90 Kts above 200 AGL?

[Boatguy]

On the 62 I see the MINSPD message frequently on takeoff. After gear up I pitch for 90 (high end of Vyse) until I get to 1,000' - 1,500' AGL, have finished any immediate turns required on departure, power back to 94% and usually engage the AP. If I dip below 90, I get the MINSPD and it only takes a little wobble to trigger the message.

I also use FLC for climbs, and VNV or VS for descents and depending on the situation I sometimes pull the power down as low as 20% on the descents. There is certainly a scenario to reach the USP limit by forgetting to power up when reaching the descent altitude. I have not yet encountered that.

Does anyone where we can find documentation on the entire ESP envelope?

[FlyingPenguin]

Does anyone where we can find documentation on the entire ESP envelope?

The ESP is documented part in the AFM (SUPPLEMENT A34 TO THE AIRPLANE FLIGHT MANUAL DA 42 NG
ELECTRONIC STABILITY AND PROTECTION (ESP)) and part in the G1000 Pilot’s Guide, under additional features. At least, that’s where I found the info. for my plane.

[Jetblast]

Interesting that I read into this a few days ago as I wanted to go test the system on a next flight. (New plane under warranty so I want to test every gizmo in it)
The pitch down to maintain 90kts is if you are in LVL, PIT, FLC, VS or VNV modes.
If you are in ALT, GS, GP, GA, the aural stall warning must be played for more than 1sec before ESP kicks in, level wings and pitch down to stop stall warning + 2 kts.
From what FlyingPenguin was saying I would guess he was in ALT mode so the second situation where he would have had to hear the stall warning before ESP would have intervene.
Obvious disclaimer: if you go try your ESP do it with lots of sky under you...

[FlyingPenguin]

Interesting that I read into this a few days ago as I wanted to go test the system on a next flight. (New plane under warranty so I want to test every gizmo in it)
The pitch down to maintain 90kts is if you are in LVL, PIT, FLC, VS or VNV modes.
If you are in ALT, GS, GP, GA, the aural stall warning must be played for more than 1sec before ESP kicks in, level wings and pitch down to stop stall warning + 2 kts.
From what FlyingPenguin was saying I would guess he was in ALT mode so the second situation where he would have had to hear the stall warning before ESP would have intervene.
Obvious disclaimer: if you go try your ESP do it with lots of sky under you...

Great find, thank you! I wasn’t aware there were different modes of when the system pitched down.

Yes, I was in ATL mode during my testing. So going to stall warning plus 2 kts. That makes sense why I saw 76 before the plane started to pitch down.

Thanks again for the info!

Peter