What was found
ON GROUND AFTER LANDING "HYD 1 LO PRESS" ILLUMINATED FOLLOWED NON NORMAL CHECKLIST. HYD FLUID NR 1 WAS EMPTY HYD, SYSTEM PRESSURE HAD SOME PRESSURE WHEN WE PULLED UP HYD PAGE ON EICAS AND BLED DOWN TO 0PSI. SHUTDOWN ENGINE NR 1 PUMP RAN FOR LESS THAN 30 SEC WITH PRESSURE. NOT SURE HOW LONG ENGINE RAN NO FLUID BUT ENGINE WAS SHUTDOWN WITHIN ABOUT 5 MINUTES OF RECIEVING THE CAUTION FOR THE "HYD 1 LOW PRESS. FOUND RUDDER PCU NR 1 FAILED REMOVED & REPLACED IAW AMM 27-23-01 OPS CHECKS GOOD AT THIS TIME