What was found
DURING CLIMB TO 14000FT, HYD LOW LIGHT ILLUMINATED. CREW MADE A TURNBACK TO BASE, AFTER INFORMING ATC. ABOUT 3 MINUTES AFTER THE TURN THE WARNING LT EXTINGUISHED. CREW BACKED UP SITUATION WITH THE ABNORMAL CHECKLIST. ON EXTENDED FINAL, USING THE BEFORE LANDING CHECKLIST, CREW NOTED A NOSE GEAR UNSAFE INDICATION. THE CHECKLIST WAS FOLLOWED, ENDING IN A LANDING WITH A THREE GREEN DOWN AND LOCKED INDICATION, WITHOUT FURTHER PROBLEMS. MAINTENANCE DISCOVERED LOOSE CAP ON RESERVOIR. REPLACED CAP, CHECKED FLUID LEVEL, PERFORMED GEAR CHECK, OPS CHECKED GOOD. RELEASED AIRCRAFT FOR SERVICE.