Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 19; Flight Crew Total 318; Flight Crew Type 141
Situational Awareness
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
General Maintenance Action
Aircraft
Intention was a dual checkout flight in a new model of the C172. After preflight inspection and engine start; instructor and myself each performed a brake check/positive exchange of flight controls. I called for taxi clearance and was instructed to taxi from my hangar to the active runway; holding short of an intersecting runway. We began taxi procedures as normal; with appropriate speeds; power settings; and brake usage. As we approached the hold short line of the intersecting runway; I began reducing power and adding brake pressure. The airplane veered to the left with equal pressure on both brakes. The instructor and myself were both standing on the right brake; but there was no effect. We exited the taxiway and rolled 5-10 feet into the grass beside the taxiway. We pulled the throttle and mixture to idle; and advised ground control that we needed assistance before turning the electrics off. The airplane and airport property were not damaged. Once we got the airplane back to the hangar; mechanic inputted additional hydraulic fluid. Was not able to detect any other problems with the brake system. Mechanic thought we had bubbles in the brake lines. No hydraulic fluid was observed on the ground or leaking out of the brake assembly prior to departure. To prevent a recurrence; I think it is important to have a thorough preflight inspection; continue checking brakes; and taxiing at safe and reasonable speeds during every ground operation. I believe it is also important to communicate about any airplane abnormalities to colleagues; supervisors; etc. Post incident discussion revealed that other pilots who flew this airplane had intermittent problems with the right brake.
A Cessna 172 Pilot reported that when the airplane was taxied and the brakes were equally applied; the airplane pulled to the left.