What was found
PILOT REPORTED PROGRESSIVELY SEVERE TAILWHEEL SHIMMY DURING LANDING ROLLOUT, LEADING TO LOSS OF CONTROL AND GROUND LOOP WITH SIGNIFICANT DAMAGE TO AIRCRAFT. POST ACCIDENT INSP FOUND THE TAILWHEEL SPRING HAD AN EXISTING CRACK FROM THE TAILWHEEL HEAD MOUNTING BOLT TO THE POINT OF TORSIONAL FRACTURE, AS EVIDENCED BY THE DIRT AND CORROSION IN THE CRACK. LACK OF ADEQUATE TAILWHEEL SYSTEM INSPECTION AND MAINTENANCE LED TO THE FAILURE OF THE TAILWHEEL STEERING, LEADING TO THE LOSS OF CONTROL, LEADING TO THE GROUND LOOP AND AIRCRAFT DAMAGE. PILOT REPORTS THE LAST ACTUAL COMPLETE DISASSEMBLY AND REASSEMBLY (COMPLETE REBUILD) MAINTENANCE ON THE TAILWHEEL WAS DONE WHEN IT WAS PLACED ON AIRCRAFT 26 YEARS EARLIER. LAST ANNUAL, THE TAILWHEEL WAS INSPECTED FOR NORMAL OPS, BEARINGS, AND ASSEMBLY GREASED AS WELL AS ON OR ABOUT 2-3 WEEKS BEFORE DEPARTURE (TO KPLK), AIR PRESSURE SERVICED, AND WHEEL ASSEMBLY GREASED. HOWEVER, NO NEW PARTS WERE REPLACED, OR HUB DISASSEMBLY WAS COMPLETED. DID HAVE A FEW FLIGHTS IN THE PREVIOUS YEAR WITH A NOTICEABLE SHIMMY BUT ATTRIBUTED THE MINOR SHIMMY TO AIR PRESSURE. WHEN THE AIR PRESSURE WAS CHECKED, IT WAS LOW. RECOMMENDED THAT THE TAILWHEEL ASSY BE DISSASSEMBLED DURING INSPECTIONS TO DETERMINE THE TRUE INTERNAL CONDITION, AS WELL AS THE TAILWHEEL SPRING CONDITION AND THE TAILWHEEL PIVOT AXIS GEOMETRY BE INSPECTED IAW MM.