What was found
REPEAT WRITE UP. ON APPROACH WE SELECTED LANDING GEAR DOWN AND A LOUD BANG NOISE HEARD & FELT FROM NLG. THE MLG INDICATORS TURNED GREEN WHILE NLG INDICATOR REMAINED YELLOW FOR A PERIOD LONGER THAN USUAL. EVENTUALLY IT TURNED GREEN. ABORTED APPROACH & EXECUTED A GO AROUND & SELECTED MLG UP AS NORMAL. NO ABNORMAL NOISE OR JARRING BANG FELT. CLIMBED TO ALTITUDE & DECIDED TO DIVERT BACK TO ORIGIN AIRPORT KDAL. ON SECOND APPROACH WHEN SELECTED MLG DOWN, WAS A SIGNIFICANTLY LESS INTENSE BANG (SEEMED MORE NORMAL) AND THE INDICATOR FOR NLG TURNED GREEN SOONER THAN FIRST APPROACH. A NORMAL LANDING WITH NORMAL BRAKING & TAXING WAS THEN SAFELY COMPLETED. REPLACED PRIORITY VALVE. OPS CHKD GOOD. IAW AMM 32-31-00-720-801-A