FATIGUE FAILURE OF THE ENGINE SPUR ADAPTER GEARSHAFT IN AN AREA WHERE THERE WAS A LACK OF LUBRICATION (OIL STARVATION) DUE TO A PARTIALLY BLOCKED OIL DELIVERY TUBE. CONTRIBUTING FACTORS WERE: INATTENTIVE MAINTENANCE OR SERVICING OF THE AIRCRAFT BY UNKNOWN MAINTENANCE PERSONNEL, THE LIGHT CONDITIONS AT DUSK, AND THE ELECTRICAL (TRANSMISSION) WIRE.