What was found
SHIP 3220 DISC: WHILE WAITING FOR BRAKES TO COOL FOR TAKEOFF WE NOTICED A SLIGHT SULPHUR ODOR THAT DISSIPATED QUICKLY. F/A THEN CALLED TO REPORT STRONG SMELL, CONCETRATED IN AFT CABIN. WE RETURNED TO GATE ASAP. F/A REPORTED SULPHUR ODOR DISSIPATING ON TAXI IN. C/A: RAN ENGINES PER AMDS CARD 7900-2001. ISOLATED RUNNING BOTH PACKS WITH EACH ENGINE AND APU AS SINGLE BLEED SOURCE. NO SMELL IN CABIN OR FLIGHT DECK (WIP 422381) COMPLIED WITH WORK CARD 7900- 2001 (CHECK CABIN FOR CFM56 ENGINE OIL FUMES ODOR) NO FINDINGS FOUND. WIP 668420. C/W WORK CARD #2100-2003 & 0550-2002 A/C READY CONT SVC. (LP: 4761289)