As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, PILOT SIDE WINDOW HAD A LOUD SOUND. PILOT ELECTED TO REPOSITION BACK TO MX BASE. MX DISCOVERED THAT A INTERIOR TRIM PANEL PIECE HAD BECOME STUCK BETWEEN THE PILOT'S CREW WINDOW AND THE WINDOW SEAL. THE PILOTS CREW WINDOW CAN BE OPENED TO COMMUNICATE BETWEEN CREW AND GROUND PERSONEL AND MUST HAVE TRAPPED THE INTERIOR PANEL WHILE CLOSING THE WINDOW. MX REPOSITIONED TRIM PANEL AND SECURED WINDOW.