What was found
HYD 1 LO PRESS ON CLIMB-OUT, COMPLIED WITH QRH, RECEIVED HYD EDP 1A CAUTION. HYD 1B SELECTED ON APPROX. 1 MIN. SELECTED OFF PER QRH, HYD 1 LO PRESS RETURNED. NO OBSERVED TEMPERATURE CHANGE IN SYSTEM. "AIRCRAFT REMOVED FROM SERVICE" INSPECTED AND FOUND LOOSE AND LEAKING B NUT IN LEFT MAIN WHEEL BIN AREA. TIGHTENED B NUT AND OPS CHECK IN REF TO AMM 29-11-03 OPS CHECK GOOD NO LEAK NOTED. SERVICED HYD SYSTEM 1 IAW AMM 12-00