Landing and Runway Excursion
The pilot of a tailwheel-equipped airplane reported making a normal landing approach to the runway in direct crosswind conditions of 15 knots with gusts to 23 knots. After touchdown on the main landing gear, directional control was initially maintained with normal flight control inputs. However, when the tailwheel contacted the runway, the tail began to weathervane and the airplane veered to the right. Despite the pilot applying full left rudder and left brake, he was unable to regain directional control, and the airplane departed the right side of the runway.
Impact and Damage
The airplane subsequently struck a precision approach path indicator (PAPI) system. The collision caused substantial damage to the left wing, left horizontal stabilizer, and left elevator.
Postaccident Examination
A postaccident examination and functional test of the steerable tailwheel revealed that the spring-actuated key slide would stick in the retracted position within the tailwheel fork. This condition allowed the tailwheel to caster instead of remaining steerable within the normal limits intended for takeoff and landing. Further inspection showed that the slot in the tailwheel fork holding the key slide was slightly deformed, and the key itself had several raised edges that caused binding when fully retracted in the slot.
Conclusion
It is likely that the tailwheel was able to caster during landing, which resulted in the pilot's inability to maintain directional control after the tailwheel had touched down during the landing roll.