Nose over after mode change

I have encountered an interesting issue where when I switch between modes the aircraft puts its nose down (approx 20 degrees) and keeps it there until I manually pull up. I first discovered the issue when i came out of autotune into FBWA after initial tuning and is replicated when going back into autotune. Once corrected the aircraft flies as it should in the mode selected. During the event we loose about 20-30m of altitude.

The setup:
Airframe: Skywalker EVE2000
Battery: 6s 8000mah
Flight control: Pixhawk “the cube” 2.1
Firmware: Arduplane 3.7.1
GPS: “Here” gps
BEC: castle creations 10a
Telemetry: RFD 900u
Airspeed sensor: Digital (I2c)

Any advice here would be great as i suspect I am missing something obvious. Log attached.

Plane 3.7.1 (and earlier) had a bug that resets the integrators on mode change. This is fixed in master (and the 3.8 betas). If your aircraft is dependent upon a large amount of integrator to fly level I would look at your trims and neutral points on the surfaces. I’d look at the log to confirm the amount of integrator used, but you forget to attach it.

Thanks for the response!
I have check (and double checked) my surfaces and they are all neutral and I am within the CG tolerance for my aircraft so not sure if thats the issue. would love to know more about the bug though just in case I’ve missed somthing.

Just because the surface is neutral mechanically doesn’t guarantee that what you have trimmed is correct for flight. I expect what your seeing is that your aircraft is either excessively nose heavy and it’s requiring a lot of compensation from your elevator to compensate for that. (Either that or you did the calibration wrong after setting up the transmitter, I’m going to guess the former is more likely). Without a log it’s hard to point at which is the culprit.

Understood. Will check the aircraft in manual mode to see if i get a nose over at the current CG (it may be the manufactures CG numbers are wrong). Can you please confirm that my log uploaded properly with the initial post?

Sorry wasn’t trying to be subtle by saying without a log, I don’t see your log attached anywhere here.

Thanks for that. The system said uplaod complete so i assumed all was well. Lets try again… Log attached

@VUAS unfortunately it didn’t show up… Maybe try a link through Drive or similar?

@WickedShell, can you shed some more light on this bug? I had a plane crash when I switched to loiter mode Link .Reading this got me wondering if this bug could’ve played any role in that. I was running plane 3.5.2. My Integrator gains are not very high though. Would appreciate any insight that would help me figure out why the plane crashed.