What was found
AS CENTER TANK FUEL APPROACH 100 LBS, FELT & HEARD VIBRATION ON FLIGHT DECK AS IF A PUMP CAVITATING. LT CENTER TANK FUEL LOW LIGHT CAME ON. TURNED LT CENTER FUEL PUMP OFF, VIBRATION CEASED. RIGHT CENTER PUMP NORMAL OPERATION NO VIBRATION. LT & RT FUEL FLOWS MATCH & ALL ENGINE INDICATIONS NORMAL. NOTICED VIBRATION ABOUT 30 SECONDS BEFORE LT CENTER LOW PRESSURE LIGHT CAME ON. SAT- 52, FLT 370. ACFT GROUNDED. IAW AMM 28-26-00-650-802 TRANS FUEL TO CENTER TANK AND TRANSFERRED FUEL FROM CENTER TANK USING LT CTR PUMP. AUTO SHUTOFF AND PUMP WORKS OK.