I'm still looking at the .DAT but it's clear the compass was not an issue
View attachment 39617
The time axis is offset 192.04 (motor start - battery on). Until the incident that starts happening at 210 the compass is normal, in fact very normal. The incident appears to be a propulsion issue with the Left Front motor/propeller. At 220 the A/C is spinning and the magMod value is to be expected.
View attachment 39618
Starting at 210 the LF is being
commanded higher with a small increase in
speed. Starting at 220
commanded is maximum (10000) and more increase in
speed. I think this is a broken prop issue. Although, it seems that there wasn't a abrupt separation. Rather, it seems like the prop broke in the interval 210 to 220.
I'm still looking at this.