As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1712 FROM TOL TO DEN. DURING CLIMB PASSING THROUGH APPROXIMATELY 4000 FT CREW HEARD A LOUD SQUEAL ACCOMPANIED BY FLUCTUATING PRESSURIZATION. AIRCRAFT RETURNED TO TOL WERE IT LANDED WITHOUT INCIDENT. FOUND L1 DOOR UPPER HINGE COVER TO BE AT FAULT, REPOSITIONED HINGE COVER AND PERFORMED CABIN PRESSURE DECAY CHECK. NO DEFECTS NOTED. AIRCRAFT WAS RETURNED TO SERVICE.