As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YYC - LEFTHAND WING, LEFTHAND FUEL TANK PANEL 522CT, PANEL REBATE WS 117.50 TO WS 157.825, FRETTING CORROSION ON TOP SURFACE OF REBATE AROUND PANEL ANCHOR NUT ATTACH HOLES. REPAIRED IAW Q400 SRM 57-10-30-320-002, RD 8/4-57-429, ISSUE 1 AND HORIZON AIR EA 6-57-308.