What was found
AIR RETURN FOR FLAP FAIL CAUTION MESSAGE FLAPS 13 INDICATION QRH FLAPS FAIL COMPLETE. 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 DECEMBE 18, 2009 AND PA AD 27-052G. FOUND LT FLAP ACTUATOR FLEX SHAFTS 1-5 DAMAGED AND RT FLAP ACTUATOR FLEX SHAFTS&5 DAMAGED, LT + RT FLEX SHAFTS WERE REPLACED IAW AMM 27-53-10. ALSO PERFORMED FLAP SYSTEM LUBE IAW CHECKLIST PROVIDED. FLAP SYS CHECKS NORMAL IAW AMM 27-50-00.