What was found
FLAPS FAIL AT 20 ON APPROACH. FLIGHT LANDED WITHOUT ADDITIONAL ISSUE. AC IS STILL OUT OF SERVICE. PERFORMED TROUBLESHOOTING PER BOMBARDIER FIM REV 39 IAW AD 2009-06-12 PARAGRAPH (H) (6) (I), AMOC DATED MARCH 27 2009, TR 27-012 PER AMOC DATED DECEMBER 18, 2009 AND PA AD 27-052B. SEE TALLY CARD DATED 5-15-2012 FOR R&R OF FECU, LT BPSU, AND RT BPSU. R&R'D LT BPSU RT BPSU AND FECU. OP CHECK GOOD IAW AMM 27-54-00.