What was found
ENGINE WAS INSTALLED AFTER O/H. GROUND RUN AND PERFORMANCE RUN WAS SATISFACTORY. ACFT WAS FLIGHT TESTED FOR 45 MINUTES, 2 TIMES WAS RUNNING GOOD. ACFT WAS DEPARTED FOR EXPORT WHEN FLEW FOR 45 MINUTES OIL PRESSURE AND TORQUE PRESSURE FLUCTUATION WERE NOTICED. ENGINE DIVERTED BACK TO THE BASE. INVESTIGATED FOR OIL PRESSURE FLUCTUATION AND TORQUE FLUCTUATION AND FOUND THAT THERE IS CONSIDERABLE OIL LOSS FROM THE SYS INTERNALLY FROM THE ENGINE AND OIL LEAK NOTICED FROM ENGINE BLEED VALVE AND MANY OTHER ENGINE CASE FITTING. ENGINE NOW DECIDED TO PULL IT OUT AND SEND FOR FURTHER INVESTIGATION AT THE O/H SHOP.