As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCI - FLT 586 - THE AIRCRAFT DEPARTED MCI AND 35 MINUTES INTO FLIGHT THE FIRST OFFICERS SLIDING WINDOW CRACKED. THE AIRCRAFT RETURNED TO MCI WITHOUT INCIDENT. MAINTENANCE PERSONNEL REPLACED THE CRACKED F/O WINDOW AND WINDOW HEAT CONTROL UNIT. (M)