As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER DEPARTURE FROM YEG, CREW REPORTED DIFFICULTY PRESSURIZING THE AIRCRAFT AND THE LT SLIDING WINDOW APPEAR TO BE NOT CLOSED PROPERLY. AIRCRAFT RETURNED TURNED BACK FROM FLIGHT AND LANDED SAFELY IN YEG. ON INVESTIGATION, FOUND THE SCUFF PLATE ON LT CD POST (FWD FRAME OF SLIDING WINDOW CUT-OUT) CRACKED AND SLIGHTLY DISLOCATED FROM ORIGINAL POSITION. THIS PLATE IS INSTALLED ONLY ON POST-MOD AIRCRAFT PER SB B737-56-1024. THIS PRESUMABLY PREVENTED THE LT SLIDING WINDOW FROM CLOSING PROPERLY CAUSING A PRESSURIZATION LEAK. (TC NR 20091202016)