What was found
IN CRUISE FLIGHT APPROXIMATELY 25 MINUTES AFTER TAKEOFF, NR 1 SERVO SYSTEM CAUTION LIGHT ILLUMINATED. RESET SERVO JAM CIRCUIT BREAKER AND LIGHT EXTINGUISHED. TWO MINUTES LATER, NR 1 SERVO SYSTEM LIGHT ILLUMINATED AGAIN. RESET SERVO JAM CIRCUIT BREAKER AND LIGHT EXTINGUISHED. AIRCRAFT TURNED BACK TO BASE. ONE MINUTE LATER, NR 1 HYDRAULIC SERVO SYSTEM LIGHT ILLUMINATED AGAIN. RESET CIRCUIT BREAKER, BUT LIGHT REMAINED ILLUMINATED. AIRCRAFT LANDED FIRST AVAILABLE PLACE. NR 1 HYDRAULIC SYSTEM WAS FOUND TO REQUIRE SERVICING. SERVICED SYSTEM AND GROUND RAN ACFT. TAIL ROTOR RETURN LINE FOUND LEAKING AT B-NUT. ACFT WAS SHUT DOWN. B-NUT FOUND BACKED OFF. B-NUT TIGHTENED, ACFT GROUND RAN AND LEAK CHECKED OK.