What was found
WAS INVOLVED IN AERIAL APPLICATION, ON A SPRAY RUN PILOT NOTICED THAT HE WAS PICKING UP VIBRATION IN TAIL ROTOR CONTROL PEDALS AND CEASED SPRAY OPERATIONS. CAME IN FOR LANDING AND AT HOVER IS WHEN THE U-JOINT FAILED. HELICOPTER TURNED 180 DEGREES BEFORE LANDING. NO DAMAGE TO AIRCRAFT. PART THAT FAILED INSPECTED DAILY. LUBRICATED EVERY 10-15 HOURS. AFTER EXAMINING FAILED U-JOINT, FOUND THAT ONLY HALF OF JOINT WAS RECEIVING ANY GREASE. DONT KNOW HOW LONG THIS CONDITION OF NO GREASE WAS HAPPENING.