What was found
COMPLETE A-SYSTEM HYDRAULIC FLUID LOSS IN FLIGHT. REPLACED O-RING P/N NAS 1612-4 ON "A" SYSTEM ELECTRIC MOTOR DRIVEN HYDRAULIC PUMP BLANKING PLUG. RESERVOIR "A" RESERVICED AND LEAK CHECKED SATISFACTORY. A RECORDS REVIEW REVEALED THAT THIS PUMP WAS INSTALLED ON 1/31/05 AFTER REPAIR AT DELTA AIRLINES. THERE ALSO WAS AN ENTRY IN THE FLIGHT LOGBOOK ON 2/5/05 WHICH STATED THE "A" SYSTEM WAS LEAKING HOWEVER GROUND MAINTENANCE DID NOT FIND A LEAK AT THAT TIME AND THE AIRCRAFT WAS RETURNED TO SERVICE. THIS PUMP ACCUMULATED 259 HRS SINCE INSTALLATION BEFORE FAILURE. IT IS SUSPECTED THAT THE O-RING WAS DAMAGED AT DELTA AIRLINES DEPT 360 DURING BUILD UP. THIS SDR CONTROL NUMBER 1290501 IS CLOSED.