What was found
MBJ/EWR - FLT JM 2019 - ACFT EXPERIENCED HIGH VIBRATION ON THE N1 OF NR 2 ENG DURING INITIAL TAKEOFF ROLL. TAKEOFF DISCONTINUED, ACFT RETURNED TO RAMP. NR 2 ENG SUFFERED FOD DAMAGES TO 2 FAN BLADES ON 9-16-99. AFTER ASSESSMENT AND APPLICATION OF A310 MM 72-21-00, ACFT RELEASED FOR 50 FLT HRS DURING WHICH BLADES WOULD BE REPLACED. PRIOR TO DEPARTURE, DAMAGED FAN BLADES REPLACED. A310 MM 72-21-02-4 FOLLOWED, 2 BLADES REPLACED IN MATCHED PAIRS. PG 3 ALLOWS A 1.0 OUNCE INCH MOMENT WEIGHT DIFFERENCE BETWEEN MATCHED PAIR OF BLADES, 1 PAIR HAD 1.0 OUNCE INCH DIFFERENCE, THE OTHER, 0.3 OUNCE INCH DIFFERENCE. WITH REQUIREMENTS OF MM MET, SUSPECT HEAVIER OF BOTH PRS OF BLADES INSTALLED ADJ CREATED IMBALANCE.