As the title says, MSU is under investigation for their use of planes operated by the state of Michigan for recruting trips by Dantonio and Izzo. The investigation began after the Lansing State Journal ran a series on the planes and how they are utilized. Over a five year period, Dantonio and Izzo combined for 102 flights on state-operated flights. As you likely assumed, The University of Michigan can handle it's own recruiting travel arrangements and is not under investigation.
FWIW. Michigan doesn't seem inclined to get re-involved.