GA pilot reported runway excursion after landing; causing damage to the aircraft.

Narrative:

During the landing rollout on runway xx at ZZZ; the [tailwheel biplane] I was operating abruptly departed from the paved runway surface onto the grass adjacent the runway. The wheel landing and initial rollout were uneventful and smooth. However; immediately after the tail wheel touched down onto the runway surface the aircraft swerved uncontrollably to the left. I reacted immediately with full right rudder trying to prevent the aircraft from departing the paved surface.as the aircraft began to exit the runway; 'at approximately 25 knots;' the lower right bow wing and lower right aileron scrapped the runway surface; damaging the wings outer edge. I added power to regain control of the aircraft approximately 10 ft left of the runway paved edge in the grass adjacent the runway. I continued maneuvering the aircraft in the grass for approximately 300 feet fortunately missing runway signs; runway lighting; and passing over a drainage ditch. I returned to the runway paved surface shortly thereafter. I taxied the aircraft back to the hangar under its own power. The weather at the field was clear; greater than 10 miles visibility; temp 73 degrees; and winds light and variable.

Original NASA ASRS Text

Title: GA pilot reported runway excursion after landing; causing damage to the aircraft.

Narrative: During the landing rollout on runway XX at ZZZ; the [tailwheel biplane] I was operating abruptly departed from the paved runway surface onto the grass adjacent the runway. The wheel landing and initial rollout were uneventful and smooth. However; immediately after the tail wheel touched down onto the runway surface the aircraft swerved uncontrollably to the left. I reacted immediately with full right rudder trying to prevent the aircraft from departing the paved surface.As the aircraft began to exit the runway; 'at approximately 25 knots;' the lower right bow wing and lower right aileron scrapped the runway surface; damaging the wings outer edge. I added power to regain control of the aircraft approximately 10 ft left of the runway paved edge in the grass adjacent the runway. I continued maneuvering the aircraft in the grass for approximately 300 feet fortunately missing runway signs; runway lighting; and passing over a drainage ditch. I returned to the runway paved surface shortly thereafter. I taxied the aircraft back to the hangar under its own power. The weather at the field was clear; greater than 10 miles visibility; temp 73 degrees; and winds light and variable.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1589623
Time
Date	201810
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	None
Person 1
Function	Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 180 Flight Crew Total 21400 Flight Crew Type 30
Events
Anomaly	Ground Event / Encounter Loss Of Aircraft Control Ground Event / Encounter Ground Strike - Aircraft Ground Excursion Runway