What was found
ON FLIGHT 4146 (LEX TO DTW) FLAP FAIL AT O 4000: -15 C AT 200 KTS TRACE ICE ONLY. NO ICE INDICATION AT TIME OF FAILURE .TOUCHDOWN 2 < 200 FPM. PERFORMED TROUBLESHOOTING PER BOMBARDIER FIM REV 44 IAW AD 2009-06-12 PARAGRAPH (L)(6)(I), PER AMOC DATED DECEMBER 07,2012 AND PA AD 27-052J PERFORMED FLAP LUBE ON LT AND RT SIDE, COMPLIED WITH "FLAP FAIL" MINIMUM WORKSCOPE, REPLACED RT O/B FLAP O/B ACTUATOR, SWAPPED BPSU'S FROM RIGHT TO LEFT FOR TROUBLESHOOTING, PERFORMED ELECTRICAL RIG OF FLAP BPSU'S AND REPLACED THE RT FLAP NR 2, 3, 4, 5 FLEX SHAFTS. WORK ON AIRCRAFT COMPLETED ON 2/2/2013.