What was found
MAIN CARGO DOOR LIGHT CAME ON AT 400 AGL DURING TAKEOFF. AIR TURNBACK TO CVG. UNEVENTFUL LANDING AND GROUNDED BY MAINTENANCE. T/S PER IAI SUPP MM 52-71-09. FOUND S9021 OUT OF LIMITS. ADJUSTED PER 52-71-09. R+R MCD DOOR CENTRAL PANEL IAW B767 IAI SUPPLEMENT AMM 52-32-20 OPERATED DOOR FULLY 3 TIMES NO FAULTS FOUND ALL INDICATIONS NORMAL. DOOR WAS VERFIED CLOSED AND DOOR INDICATION SYSTEM DEFERRED IAW MEL52-71-1-2 AIRCRAFT RELEASED.