I fly corporate jets and any of my quad copters would seriously damage the engines if they were ingested. The 4 motors alone would cause major damage to the fan and turbine blades.

They are designed to continue operating if a small bird is ingested but this can still bend a blade that causes vibration and other problems and would require maintenance.

And don't forget Cactus 1549 in the Hudson, that was brought down by geese.