What was found
UNUSUAL THUMPING NOISE COMING FROM UNDERNEATH COCKPIT AREA. HAPPENED ON TWO SEPARATE TIMES WITH VIBRATION FELT BY BOTH PILOTS. REMOVED AND REPLACED NLG UPLOCK BOX IAW AMM 32-33-07. REMOVED AND REPLACED HARNESS TO NLG UPLOCK BOX FOR INTERNAL SHORT IAW SWPM 20-10-00, 20-13-02 AND 20-50-00. RIG, LEAK AND OPS CHECK GOOD IAW AMM 32-34-00 AND 32-30-00.