What was found
DURING CRUISE THE FLIGHT CREW NOTICED A SLOW LOSS OF B SYSTEM FLUID, DUE TO A DECREASE IN PRESSURE. SECURED REMAINNG B PUMP. SYSTEM FLUID REMAINED, NO SYSTEM OVERHEAT. HYDRAULIC PLUG AT NR 4 SLAT ACTUATOR WAS FOUND TO HAVE A BLOWN OUT SEAL. REMOVED AND REPLACED SEAL, SYSTEM LEAK CHECKS GOOD. NOTE HYDRAULIC SYSTEM WAS NOT DEPLETED, LOW PRESSURE OR HEAT TEMPERATURE LIGHT DID NOT ILLUMINATE.