What was found
ON SEPTEMBER 20, 2021 N924PS DEPARTED EMPTY FROM KDAL HEADING TO KMAF. THE CAPTAIN NOTICED THE LH ENGINE OIL PRESSURE INDICATOR SHOWED ZERO PSI AND THE LOW OIL PRESSURE LIGHT ON THE ANNUNCIATOR PANEL WAS ON. HE MOVED THE THROTTLE LEVER TO IDLE THEN TO CUTOFF AND REQUESTED A RETURN TO KDAL. AFTER LANDING SAFELY AT DAL, MAINTENANCE WAS CALLED TO INVESTIGATE THE LOSS OF OIL PRESSURE. DALLAS AIRMOTIVE INFORMED ATI MAINTENANCE THAT THE ENGINE AND COWLING WERE OIL SOAKED. NO DEFINITIVE CAUSE OF LOSS OF OIL AND OIL PRESSURE COULD BEEN DETERMINED. OIL WAS ADDED AND ENGINE WAS MOTORED - SLIGHT OIL PRESSURE WAS INDICATED. AN ENGINE START WAS ATTEMPTED AND MAINTENANCE THOUGHT A "HUNG" START RESULTED. WITH FURTHER INVESTIGATION, MAINTENANCE FOUND THAT THE N1 STAGE HAD SEIZED. THE ENGINE WILL BE REMOVED FROM THE AIRCRAFT AND DISASSEMBLED TO TRY TO DETERMINE THE CAUSE.