What was found
DURING T/O A BURNING RUBBER ODOR AND SMOKY HAZE BEGAN TO FILL THE COCKPIT AND CARGO AREA. RED TABS FOLLOWED AND A/C INITIATED RETURN TO BASE. INSP'D FOLLOWING AREAS FOR PROBLEMS, BOTH E & E BAYS, A/C PACK BAYS, AFT AIRSTAIRS, GEARWELLS, SNAKE PIT IN FWD BELLY, CAPTS, & F/O INSTRUMENT PANELS COCKPIT OVERHEAD, PEDESTAL, C/B RACKS & RUBBER PEDAL AREA. CK'D GASPER FAN OPS, W/APU RUNNING. OPS BOTH PACKS, RAN ALL ENG & C/W PNEU & A/C CKS, AIR CLEANER SYS CK, PNEU SYS CK, PRESS CONT SYS CK TEST, AUTO PACK TRIP CK, SIMULATED T/O & CLIMB PWR SETTINGS & PACK OPS NO DEFECT/PROBLEMS. ONLY CK NOT DUP WAS T/O.