What was found
FLT 280 - MDW-GRR - LIGHT SMOKE AND ODOR EMANATED. CREW SHUT OFF FLOWS SMOKE SUBSIDED. ATC WAS NOTIFIED. AIRCRAFT RETURNED TO MDW WITHOUT FURTHER INCIDENT. AIRCRAFT WAS THEN FERRIED TO GRR. FLOWS DEFERRED. INSPECTION FOUND CRACKED Y-DUCT BLOWING AIR ON RESIDUAL HYDRAULIC FLUID BELOW BELLY OF AIRCRAFT. REPLACED DUCT AND CLEANED UP FLUID. AIRCRAFT RETURNED TO SERVICE. AIRCRAFT TOTAL TIME HOURS 19165.5. (M)