As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OIL PUMP SHAFT SHEARED THUS UNCOUPLING THE FUEL PUMP FROM THE ENGINES GEARBOX. THE CRACK THAT CAUSED THE EVENTUAL SHEARING OF THE GEARSHAFT APPARENTLY ORIGINATED AT A SLOT FOR THE LOCKING KEY THAT WAS MACHINED DURING A PAST REWORK (MODIFICATION) THAT HAD BEEN DONE TO THE PUMP. (SW05200400286)