LANSING, Mich. (AP) - Michigan Department of Transportation officials say they haven't violated federal regulations by allowing Michigan State University coaches to use the state's passenger planes for athletic recruiting trips. The Lansing State Journal reports MDOT's response to a Federal Aviation Administration preliminary investigation was detailed in documents sent to the FAA this month. The inquiry came after the newspaper published a series on the taxpayer-funded planes. The FAA review could trigger a formal FAA investigation. A letter from MDOT suggests two concerns from the FAA - that the Athletics Department isn't eligible to use state planes because it is a self-sustaining division of the university, and that MDOT should have a certificate to provide services outside state government. MDOT spokesman Jeff Cranson says the state hasn't done anything wrong.