What was found
FLT # 811, BOS-ORD(EMERGENCY DECLARED). HYD 1 LO QTY EICAS AT 36000. HYD 1 LO PRESS EICAS DESCENDING THROUGH 28000; FOR CORRECTIVE ACTION REFERENCE LP 4707576 ITEM 1 & 2 R/R OF PRIORITY HYD VALVE AND R/R OF ENG 1 EDP; FOUND MAJOR LEAK FROM LANDING GEAR PRIORITY VALVE R+R VALVE OPS CHECK GOOD IAW AMM 29-11-12.UPON INSP OF THE #1 HYDRAULIC SYS FOUND THE CASE DRAIN FILTER WITH METAL DEBRISR/R ENG #1 EDP IAW AMP 29-11-01 LEAK AND OPS CHECKS GOOD. NO DEFECTS NOTED ALS OFIF A FLUSH OF THE #1 HYDRAULIC SYS AND R/R ALL FILTES IAW AMP 29-10-00 PRESS AND QTY HOLDING NO DEFECTS NOTED AC GOOD FOR SVC