What was found
NR 1 ENGINE INDICATED OIL PRESSURE WAS BELOW 40 PSI. PERFORMED INFLIGHT SHUTDOWN OF NR 1 ENGINE. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED NR 1 ENGINE. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE. TEARDOWN RESULTS OF ENGINE SHOW A FAILURE OF AN LP BLADE DUE TO A FRACTURE JUST ABOVE THE ROOT, WHICH CAUSED THE BALDE TO TRAVEL THROUGH THE GAS PATH. AN OUT OF BALANCE CONDITION RESULTED CAUSING ADDITIONAL ENGINE COMPONENT FAILURES.