What was found
ETOPS SIGNIFICANT SYSTEM - OBSERVED PERIODIC SURGE OF LEFT ENGINE, ROUGHLY 30 CYCLES PER MINUTE, ALL POWER SETTINGS. EPR +/- 0.01, N1 +/- 0.2, FF +/- 100 LBS/HR, OIL PRESSURE +/- 2 PSI. CONTINUOUS. PERFORMED FIM TASK 73-21 FAULT TREE 827 FOUND CONTAMINATION IN FUEL FILTER ELEMENT, REPLACEMENT OF PUMP & FMU REQUIRED. REMOVED LT FMU AS PER AMM 73-21-01-004-002. REMOVED LT ENG FUEL PUMP AS PER AMM 73-11-01-004-001. INSTALLED LT ENGINE FUEL PUMP IAW AMM 73-11-001-404-018-H03 AND FMU IAW AMM 73-21-01-404-001. PERFORMED ENGINE GROUND RUN, OPS AND LEAK CHECK GOOD. OK FOR SERVICE.