What was found
CREW RECEIVED FLAP FAIL ON APPROACH INTO ORD AT 0. CREW BROKE OFF APPROACH AND ARE NOW GETTING READY GET BACK ON FINAL. FLAPS FAIL CAUTION MESSAGE WHEN FLAPS WERE SELECTED ZERO TO 8 DEG IN FLIGHT. FLAPS FAILED AT ZERO DEGREES PEAK BTMS 6,4,9,7. QRH WAS C/W FLAPS FAIL LANDING PERFORMED. FLAPS WERE ALREADY ON MEL FROM TWO FLIGHTS PREVIOUSLY. AFTER EMERGENCY DEBRIEF, MX PULLED CODES AND A/C IS FERRYING TO MKE FOR REPAIR. EMERGENCY WAS DECLARED. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED RT BPSU, IAW AMM 27-51 00 FLAP OPERATION CHECKS GOOD. REMOVE PLACARD AND REMOVE FROM MEL.