TM10-3930-660-20 5-10. FUEL/HYDRAULIC TANK - SERVICE (Cont‘d) SERVICE BY DRAINING AND FILLING TANK WITH HYDRAULIC OIL Hydraulic side of fuel/hydraulic tank (1) contains 55.6 gallons of hydraulic oil  when  full. 1. 2. 3. PLACE ALL HYDRAULIC CYLINDERS IN RETRACTED  POSITION  . REMOVE DRAIN PLUG (4) FROM HYDRAULIC OIL SIDE OF FUEL/HYDRAULIC TANK (1) AND ALLOW HYDRAULIC OIL TO  DRAIN. a. b. co d. Open cap (5) at top of fuel/hydraulic tank (1) . Place suitable drain pan under hydraulic oil side of fuel/hydraulic tank (1). Remove drain plug (4) from hydraulic side of fuel/hydraulic tank (1). Allow hydraulic oil to drain completely. INSTALL DRAIN PLUG (4) TO HYDRAULIC OIL SIDE OF FUEL/HYDRAULIC TANK (1) AND FILL TANK (1) WITH HYDRAULIC OIL. a. b. c. Install drain plug (4) to hydraulic oil side of fuel/hydraulic tank (l). Fill hydraulic oil side of fuel/hydraulic tank (1) with hydraulic oil until oil level is visible in the upper sight gauge  (6). Install cap (5) at top of fuel/hydraulic tank (1). 5-23