The de-icing boot system is prone to intermittent failure in flight. When I flew them the operating theory was that the DDVs were freezing in position. Of course by the time you landed and tested the bloody thing would work fine.
I seem to remember occasional de-ice mat failure on the props.
The thing would also constantly pop fasteners during the day which would require engineers to come out with steps.
The computer for the alpha vanes whatever it was called (ADC?) would occasionally throw a wobbly and ping up with a fault on touchdown.
TCAS used to also die every so often. Haven’t flown the thing now for a while so some of these failures may have been ironed out but if I remember the fleet technical pilot bemoaning the lack of support from Canada when it came to making any changes in spite of there being ample evidence of the need to.