What was found
28.05.2021 23:18 REJECTED TAKEOFF DUE TO L PACK LIGHT ON IN TAKEOFF ROLL. AIRCRAFT REJECTED TAKEOFF AT 30 KNOTS DUE TO LEFT PACK LIGHT ON IN TAKEOFF ROLL WHEN ADVANCED THRUST LEVERS LIGHT EXTINGUISHED AFTER TRIP RESET. MAINTENANCE PERSONNEL PERFORMED REVISION TO LEFT AIR CONDITIONED PACK, DETECTING THAT THIS REPORT WAS DEFERRED PREVIOUSLY BY MEL 21-44-C CAT D. THE WO’S 7497338 AND 7498042 WERE ISSUED TO PERFORM PERMANENT REPAIR. LEFT PACK LIGHT TURNED ON WITHOUT MASTER CAUTION RECALL 215 201 41, COMES ON WHEN ADVANCING T/L TO TAKEOFF THRUST; FAN BYPASS CHECK VALVE WAS MISSING AND IT WAS DEFERRED BY MEL 21-44-C, CAT D AND LEFT PLENUM ASSY PRIMARY HEAT EXCHANGER WAS REPLACED IAW AMM 21-51-03, TESTED CORRECT.