What was found
CREW REPORTED RUMBLING NOISE DURING CRZ. RUMBLE SEEMS TO APPEAR CLOSE TO IDLE, LT ENG N1 VIB INDICATION AT 1.5, RT ENG AT 0.5. SAMC TEXT: ECM CRZ SNAP SHOTS SHOW "VIBF" FOR LEFT ESN.222130 AT 4.8, REF FIM 71-05 TASK 821 FOR T-SHOOTING. CHECK INLET, EXHAUST, CHIP DETECTORS FOR OBVIOUS DEFECTS, IF NO OBVIOUS PROBLEMS FOUND LUBRICATE FAN BLADES, ONE AT A TIME USING LUBE 4500-10 PCN (843-0045) IAW AMM. C-DETECTORS ARE GOOD. STARTING/COMPLETED BLADE LUBE. ACP INLET AND EXHAUST AND MASTER CHIP DETECTOR CHECK ON NR1 ENG. ACCOMPLISHED SUCCESSFUL VERIFICATION FLIGHT.