What was found
AFTER LEVEL OFF RECEIVED A LEVEL 1 HYD 3 OFF, ACCOMPLISHED AOM PROCEDURE. HYD 3 BEGAN TO SLOWLY DECREASE FROM 11.4 TO 10.7 GALLONS. AIR TURN BACK ACCOMPLISHED. TROUBLESHOT IAW FIM 29-10-18, NO FAULT FOUND, NO EXTERNAL LEAK. R & R HSC IAW AMM 29-0 8-01 AND RTS TEST PASSED, TROUBLESHOT IAW FIM 29-10-0 6, FOUND AIR LEAK FROM PRV UPSTREAM CLAMP, TIGHTEN BY TWO TURNS AND B-NUT ON PRV SNSNG LINE-RETIGHTEN. RAN ENG & CHECKED HYD TEMP/QTY, NO CHANGES NOTED.