What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) The aircraft departed jnx on a part 91 post maintenance functional check flight. The preflight and run-up was completed with no discrepancies. The aircraft departed the runway and began to climb. Approximately 1 1/2 miles from the departure end of the runway, at approximately 1500' the left engine began to shake violently up and down. The pilot reduced the left throttle to the idle position. Quickly thereafter a loud "pop" was heard and the left propeller separated from the aircraft. The pilot noted the propeller rotating ahead of the aircraft and descending with all three blades attached to the hub. The pilot immediately entered a left downwind for return to jnx and completed a shutdown of the left engine. The aircraft was landed at jnx with no other difficulties. The pilot shut the aircraft down and safely egressed the aircraft.
As the FAA filed it
(-23) THE AIRCRAFT DEPARTED JNX ON A PART 91 POST MAINTENANCE FUNCTIONAL CHECK FLIGHT. THE PREFLIGHT AND RUN-UP WAS COMPLETED WITH NO DISCREPANCIES. THE AIRCRAFT DEPARTED THE RUNWAY AND BEGAN TO CLIMB. APPROXIMATELY 1 1/2 MILES FROM THE DEPARTURE END OF THE RUNWAY, AT APPROXIMATELY 1500' THE LEFT ENGINE BEGAN TO SHAKE VIOLENTLY UP AND DOWN. THE PILOT REDUCED THE LEFT THROTTLE TO THE IDLE POSITION. QUICKLY THEREAFTER A LOUD "POP" WAS HEARD AND THE LEFT PROPELLER SEPARATED FROM THE AIRCRAFT. THE PILOT NOTED THE PROPELLER ROTATING AHEAD OF THE AIRCRAFT AND DESCENDING WITH ALL THREE BLADES ATTACHED TO THE HUB. THE PILOT IMMEDIATELY ENTERED A LEFT DOWNWIND FOR RETURN TO JNX AND COMPLETED A SHUTDOWN OF THE LEFT ENGINE. THE AIRCRAFT WAS LANDED AT JNX WITH NO OTHER DIFFICULTIES. THE PILOT SHUT THE AIRCRAFT DOWN AND SAFELY EGRESSED THE AIRCRAFT.