On August 3, 2018, about 0815 central daylight time, a Columbia Aircraft Manufacturing LC41-550FG, N2546B, departed the taxiway and collided with a taxiway sign while taxiing at Dallas-Fort Worth International Airport (DFW), Dallas, Texas. The private pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to and operated by Reitz Offshore Logistics, LLC, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. Day visual meteorological conditions prevailed for the cross-country flight that departed Wiley Post Airport (PWA), Oklahoma City, Oklahoma, about 0715.According to the pilot, after an uneventful landing on runway 17L he was issued taxi instructions to a fixed base operator (FBO) on the general aviation ramp. The pilot reported that the taxi was uneventful until the right turn from taxiway K to taxiway Z. He stated that the airplane did not respond to a full application of right rudder and brake pedal. Additionally, an application of the left brake pedal did not slow the airplane. The airplane departed the taxiway and went into a grass median where the right wing impacted a lighted taxiway sign. A postaccident examination of the airplane was completed by Federal Aviation Administration (FAA) inspectors with the North Texas Flight Standards District Office. The upper and lower composite skins of the right wing were fractured and crushed over an area measuring about 2.5 ft wide. The airplane was not equipped with nosewheel steering and relied on differential brake input to steer the airplane while on the ground. The FAA inspectors noted that the brake pads for both main landing gear brake pads were worn excessively, which allowed brake fluid to leak past their respective O-ring seals when the brake pedals were depressed. Additionally, the right main tire was deflated and exhibited rotational scoring where the wheel rim had contacted the tire.