As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE, A LOAD SQUEAL STARTED COMING FROM THE COCKPIT EMERGENCY ESCAPE HATCH. AIRCRAFT RETURNED TO FIELD WITHOUT FURTHER INCIDENT. UPON INSPECTION, MAINTENANCE DETERMIND THAT THE ACRYLIC COVER ON THE ESCAPE HATCH HAD BROKEN. MAINTENANCE REMOVED AND REPLACED THE ACRYLIC COVER.