FAILURE OF THE PROPELLER HUB DUE TO PREVIOUS DAMAGE, WHICH RESULTED IN SUBSEQUENT FATIGUE FAILURE OF THE HUB; AND FAILURE OF THE PILOT TO MAINTAIN FLYING SPEED, WHICH RESULTED IN A STALL AND SUBSEQUENT IMPACT WITH THE GROUND. INADEQUATE MAINTENANCE/INSPECTION OF THE PROPELLER HUB (AFTER THE PROPELLER STRIKES) WAS CONSIDERED TO BE A CONTRIBUTING FACTOR.