What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(.4) The pilot, flying from the front seat, was aware of a tailwheel shimmy condition prior to the flight. Upon touchdown, the a/c tailwheel began to oscillate. Marks on the runway showed tailwheel tires scuffing from the touchdown area and beyond. A second solid scuff mark associated with the left wheel was observed as both scuff marks diverged left of the runway centerline. Post-crash examination revealed that the right rear brake-pedal had disconnected from the connecting rod to the forward right brake-pedal and the disconnection rendered the forward right brake-pedal unusable. The disconnection occurred at the right brake-pedal attach eye, and one separation surface was observed to be clean whereas the opposing side was dirty. Cracks were observed inside the attach eye radii, as well as the opposing end of the pedal. The right-main landing gear separated. Examination of the tailwheel assembly revealed that the hexafonal nut which holds the inner lock ring in place had become loose allowing the lock ring to shift. This allowed the two lock ring pins to shear, thus allowing the tailwheel to oscillate or 'shimmy' during roll. (-23)see ptrs SEA98LA087
As the FAA filed it
(.4) THE PILOT, FLYING FROM THE FRONT SEAT, WAS AWARE OF A TAILWHEEL SHIMMY CONDITION PRIOR TO THE FLIGHT. UPON TOUCHDOWN, THE A/C TAILWHEEL BEGAN TO OSCILLATE. MARKS ON THE RUNWAY SHOWED TAILWHEEL TIRES SCUFFING FROM THE TOUCHDOWN AREA AND BEYOND. A SECOND SOLID SCUFF MARK ASSOCIATED WITH THE LEFT WHEEL WAS OBSERVED AS BOTH SCUFF MARKS DIVERGED LEFT OF THE RUNWAY CENTERLINE. POST-CRASH EXAMINATION REVEALED THAT THE RIGHT REAR BRAKE-PEDAL HAD DISCONNECTED FROM THE CONNECTING ROD TO THE FORWARD RIGHT BRAKE-PEDAL AND THE DISCONNECTION RENDERED THE FORWARD RIGHT BRAKE-PEDAL UNUSABLE. THE DISCONNECTION OCCURRED AT THE RIGHT BRAKE-PEDAL ATTACH EYE, AND ONE SEPARATION SURFACE WAS OBSERVED TO BE CLEAN WHEREAS THE OPPOSING SIDE WAS DIRTY. CRACKS WERE OBSERVED INSIDE THE ATTACH EYE RADII, AS WELL AS THE OPPOSING END OF THE PEDAL. THE RIGHT-MAIN LANDING GEAR SEPARATED. EXAMINATION OF THE TAILWHEEL ASSEMBLY REVEALED THAT THE HEXAFONAL NUT WHICH HOLDS THE INNER LOCK RING IN PLACE HAD BECOME LOOSE ALLOWING THE LOCK RING TO SHIFT. THIS ALLOWED THE TWO LOCK RING PINS TO SHEAR, THUS ALLOWING THE TAILWHEEL TO OSCILLATE OR 'SHIMMY' DURING ROLL. (-23)SEE PTRS SEA98LA087
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.