As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON ARRIVAL, MX DISCOVERED THAT THE L/E SLAT NR 4 (LT WING) OVERPRESSURE PANEL WAS OPEN. FURTHER INSP REVEALED THAT THE THERMAL ANTI-ICE INSTERSTITIAL DUCT WAS DAMAGED AND HAD IN FACT SEPARATED AT THE JOINT WITH THE ADJOINING SLAT ANTI-ICE DUCT WHILE IN FLIGHT. THE DUCT`S RUBBER O-RING/SEAL AND CLAMP WERE MISSING ALTOGETHER AND WERE SUSPECTED LOST DURING FLIGHT.