What was found
FLT 6540 - DCA-LGA - DIVERTED TO JFK, AFTER TAKEOFF AND FLAP RETRACTION, EXPERIENCED HYDRAULIC SYSTEM 'B' FAILURE, HYDRAULIC BRAKE PRESSURE NORMAL. ACCOMPLISHED ABNORMAL PROCEDURE. REPLACED NR 1 'B' SYSTEM HYDRAULIC PUMP, NR 1 AND 2 'B' PUMP PRESSURE AND CASE DRAIN FILTERS IAW MM 29-12-11 AND 29-12-21, SERVICED HYDRAULIC SYSTEM PER GMM 8-13-3. (M)