What was found
UPPER FUSELAGE ADF ANTENNA HAS PITTING CORROSION AROUND OUTER EDGES. AIRCRAFT REMOVED FROM SERVICE. REMOVED CORROSION ON UPPER SKIN FS 409+64 TO FS 409+80, STR 1L AND STR 1R. REMOVED AND REPLACED SOLID FASTENER AT BLENDED AREA, REF ASAP EA: AWAC-CRJ253-01540 REV: B, ISSUE DATE: 12/12/2020. PERFORMED HFEC INSPECTION ON UPPER FUSELAGE BLENDED AREA AT ADF ANTENNA MATING SURFACE FS 409+64 TO FS 409+80, STR 1L TO STR 1R, REF ASAP EA: AWAC-CRJ253-01540 REV: B, ISSUE DATE: 12/12/2020 AND CRJ 200 PART 1 REV 42 NDTM 51-20-06, NO INDICATIONS NOTED. EDDY CURRENT TESTER S/N 200051301 CAL DUE: 01/24/20. PERFORMED UT THICKNESS MEASUREMENT AT BLENDED AREA WHERE NOMINAL THICKNESS MEASURES .045, REMAINING THICKNESS .044. PERFORMED UT THICKNESS MEASUREMENT AT BLENDED AREA WHERE NOMINAL THICKNESS MEASURES .058, REMAINING THICKNESS .047, REF ASAP EA AWAC CRJ253-01540 REV. B, DATED: 12/12/2020. UT GAGE S/N 151136107 CAL DUE: 09/16/2021. APPLIED SURFACE PROTECTION, REF CRJ 200 SRM 51-21-11 REV 38.