Date: 201509
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
ATC / advisory: Tower ZZZ
Aircraft component: Tail Wheel
Component problem: Failed
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway; Ground Incursion Taxiway
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Aircraft configured for full flap; full stall; 3 point landing (conventional gear aircraft). Upon touchdown aircraft immediately veered left. Full right rudder and brake was applied; and left turn stopped; but angle to the runway could not be corrected with brake. As aircraft approached left edge of paved runway; called tower and said [call sign] has a problem. Tower did not respond and continued to talk to aircraft in the pattern. I believe the tower frequency was very busy and that they might have missed my call. As aircraft approached edge of runway; I saw runway lights approaching; so reduced right brake and allowed aircraft to veer more to the left. Departed runway into the grass going down a small grade and missed all lights and markers. Again called tower announcing I have a problem. Speed when departing the runway was about 15 MPH. Went off the brakes and allowed aircraft to go down grade at about a 45 degree angle to the runway and the aircraft almost came to a stop. Added power and taxied up the grade to Taxiway Bravo. Tower called back; asking all aircraft on frequency to stand by; and asked if I needed assistance. I told tower I did not; but that I needed to check the tail wheel. They gave me permission to stay in place. I departed the aircraft and inspected the tail wheel and saw that the tail wheel lock was damaged. Went back into cockpit; and disengaged tail wheel lock; then went back to tail wheel to inspect. At this time called tower on cell phone from back of aircraft and told them of problem and that all appeared well with no damage that would keep me from taxi to hangar. Tower asked me to contact them on radio. Got back into aircraft and contacted ground. Given clearance to taxi back to hangar. After putting aircraft back into hangar; inspected tail wheel lock and found one dog-ear to be broken and missing and the other bent. This allowed the tail wheel to swivel one direction only; which is what caused the veer to the left upon landing; without being able to correct the veer and bring the aircraft back to runway heading. All runway lights; taxiway lights and other obstacles were missed. No damage was inflicted to the aircraft. Basically took a short cut to taxi way over the grass.




Synopsis: The pilot of a tail-wheeled aircraft described a runway excursion due to a failed tail wheel lock that caused loss of control during landing rollout.