What was found
AFTER TAKEOFF, CREW WAS UNABLE TO RETRACT THE T/E FLAPS PAST 5 DEGREES, AND HAD A T/E DRIVE MESSAGE. DECISION WAS MADE TO RETURN TO DTW, 170,000 LBS OF FUEL WAS DUMPED. A YELLOW EMERGENCY WAS DECLARED FOR LANDING, AND A/C LANDED WITHOUT INCIDENT. DTW MAINTENANCE REMOVED AND REPLACED ALL 3 RVDT'S FOR THE OUTBOARD FLAP SYSTEM. OPERATIONAL CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.