What was found
(CAN) DURING T/O ROLL OUT AT 70 KTS NR 3 ENG OIL BYPASS LIGHT ILLUMINATED. REJECTED T/O INITIATED, A/C SLOWED, LIGHT WENT OUT. RETURNED TO GATE FOR MX TO INVESTIGATE. MX INSPECTED ENG & CARRIED OUT ENG RUN WITH NO FAULT FOUND. A/C RETURNED TO SERVICE. A/C DEPARTED WITH NO FURTHER PROBLEMS. DURING NEXT T/O OUT, NR 3 OIL BYPASS LIGHT AGAIN ILLUMINATED & AGAIN WHEN A/C SLOWED, LIGHT WENT OUT. ALL OTHER ENG INDICATIONS NORMAL & ELECTED TO ATTEMPT ANOTHER T/O. DURING SECOND T/O, BYPASS LIGHT CAME ON. RETURNED TO BLOCKS. MX INSPECTED ENG INCLUDING OIL FILTER & FOUND FILTER CONTAMINATED. FILTER REPLACED & ENG RUN CARRIED OUT WITHOUT FAULT. ACFT RETURNED TO SERVICE WITH NO FURTHER PROBLEMS DURING REMAINING FLTS.