What was found
AIRCRAFT WAS GROUNDED: IN CRUISE HYD B PRESSURE DROPPED TO ZERO. DROPPED FROM 20 TO 10% IN 10 MINUTES. ZERO SHORTLY THERE AFTER. ALTERED BY DELLOIACONO 437809 STA DFW 12 AUG 26 AFTER SPEAKING WITH INBOUND CAPT. QTY WENT TO ZERO. MIC NUMBER 7 574321 "IN CRUISE HYD B PRESSURE DROPPED TO ZERO. DROPPED FROM 20% TO 10% IN 10 MINUTES". POST FLIGHT WALK AROUND SHOWED HYDRAULIC FLUID FROM THE WHEEL WELL TO THE APU. LARGE QUANTITY OF FLUID IN WHEEL WELL. FLUID ON NUMBER 2 TIRE. MISTIFIED HYDRAULIC FLUID ALSO PRESENT IN WHEEL WELL. MAINTENANCE FOUND RH WHEEL WELL ACOUSTIC FILTER LEAKING. REPLACED ACOUSTIC FILTER. ALL DONE IAW MM 29-11-27.