Level feature pitching up

[BenUK]

Hi,
I have a new Skyview autopilot installation, it’s still in the flight testing stage, so I’m still fine tuning things. On the whole it’s going well. But… one issue I have is when I press LEVEL it pitches up, climbs about 200ft and then it’s like it realises the mistake and pitches back down. Then it flys straight and level just fine.
Does anyone know what setting would need adjustment?

 

[Rhino]

Need more info. Are you trimmed for straight and level flight, with no autopilot mode engaged, before pressing LEVEL? Or is the autopilot already on?

 

[BenUK]

Trimmed straight & level. AP is not engaged.

Press Level, it pitches up, climbs, then pitches down to recover the Alt where the level but was pressed

 

[Rhino]

HDX? What software version? Trim motors installed? Trimamp installed? If you have trim motors, have you tried disabling auto-trim? Simplified or Expert mode? What AP mode is being engaged? Any servo slip messages? Nav source? Any ADAHRS issues?

They don't match your aircraft, but there are several other threads where pitch settings are addressed. Maybe they could give you a clue. This is one of them:

Pitch Bucking during VNAV Approach

I was out doing some practice approaches in my RV10. I typically run 100 knots during approaches. I am running the latest software\firmware. Until today I have been quite satisfied with the A\P performance. I did a lot of tuning about 6 months ago and have been quite happy. Today was...

forum.flydynon.com

 

[BenUK]

Skyview, not HDX. Latest firmware.

Yes Ray Allen trim motors.
Yes auto trim enabled.
Expert mode
No servo slip
NAV source is Dynon GPS
No Issues on screen.

I have installed exactly the same hardware to exactly the same aircraft type a few times now, never seen this issue before. I have exactly the same AP settings / config as previous installations.

 

[Rhino]

HDX is a Skyview version. What Skyview version do you have? Classic? Touch? SE? Sounds like this is a new install. Is there a trimamp? Try disabling auto-trim just for testing purposes.

 

[BenUK]

Classic.
To confirm, I said it’s a new installation in the original post.
No trimamp.
I do not think I’m dealing with a trim issue, the pitch up happens immediately and abruptly as soon as Level is pressed. The trim motor can not move fast enough to be the issue. There are no stick forces when the AP engages with the Level option, so I wouldn’t expect it to start running the pitch trim motor in any case. If I trimmed pitch up manually I couldn’t recreate the pitch change speed, the trim motor simply doesn’t move quick enough.

I’ll will try with auto trim disabled to confirm this though.

 

[Rhino]

Wouldn't hurt. Sorry I missed the new installation comment.

There have been several comments about pitch bucking with new software releases, not just the one I posted above. I can't help but wonder if this is related somehow. What software version are you running?

And as Marc noted in that other thread, check for play between the elevator pushrod and servo arm.

 

[834014986]

I have the same pitch up issue with the level button. All else in the auto pilot works perfectly including hold when the autopilot is engaged. I have a classic Skyview and Ray Allen trim, works perfectly. I quit using the level function.

 

[maartenversteeg]

A question, the pilot;s User Manual says: Press the LEVEL button to engage the autopilot in Level mode. For safety in emergency situations, subsequent presses of the LEVEL button do not disengage level mode (unlike other AP mode switches). The level button transitions to 'STRAIGHT' mode which holds the aircraft in a wings level attitude. A slight initial increase in altitude doesn't seem to violate the intend of this button, it is presumably not the button to initiate a level flight when the pilot decides that the the plane climbed to a desired altitude. Or am I missing something here?

 

[Rhino]

Level mode is supposed to immediately institute a zero bank angle and zero vertical speed. A 200 foot climb would seem to violate that intent.

 

[djones]

The primary reason for a climb or descent when LEVEL is pressed, is usually due to the ADAHRS not being level with the airframe.
The autopilot will attempt to first level the ADAHRS on both pitch and roll when you press the button. If it is mounted slightly nose down, it will result in a climb and vice versa. BTW, adjusting the pitch attitude indication on the PFD will not resolve this issue. You have to physically shim the ADAHRS.

 

[Homeap]

I have the same pitch up issue with the level button. All else in the auto pilot works perfectly including hold when the autopilot is engaged. I have a classic Skyview and Ray Allen trim, works perfectly. I quit using the level function.

I have the same pitch up issue with the level button. All else in the auto pilot works perfectly including hold when the autopilot is engaged. I have a classic Skyview and Ray Allen trim, works perfectly. I quit using the level function.

I have a 2012 RV 12 with a single Skyview touch 10” display and do not have a separate panel for the auto pilot control. I am new to using the auto pilot but notice a continuous 200 ft./min. descent when pressing the level button.
What buttons do you press to get straight and level If you are not using the level button?

 

[GKC Aviation]

If you are in simplified mode, then just press the "TRK+ALT" button. This will maintain your current track, and hold the altitude you are at.
If you are in expert mode, then press "AP" and then "HDG" or "TRK", and "ALT HOLD"

If you are new to the autopilot, I would suggest you put it in simplified mode until you are comfortable with everything.

Have a read of the pilots guide. The autopilot operation section explains everything really well.

https://www.dynonavionics.com/includes/guides/SkyView_HDX_Pilots_User_Guide-Rev_D_v15_4.pdf

 

[Homeap]

If you are in simplified mode, then just press the "TRK+ALT" button. This will maintain your current track, and hold the altitude you are at.
If you are in expert mode, then press "AP" and then "HDG" or "TRK", and "ALT HOLD"

If you are new to the autopilot, I would suggest you put it in simplified mode until you are comfortable with everything.

Have a read of the pilots guide. The autopilot operation section explains everything really well.

https://www.dynonavionics.com/includes/guides/SkyView_HDX_Pilots_User_Guide-Rev_D_v15_4.pdf

Excellent, that answers my question and I will do that. Thank you so much for your assistance I do appreciate it!