Wing Tip Brakes Electro-hydraulic pressure-on disk- brakes, identified as Wing Tip Brakes,are installed near the end of the transmission system on both the slats and the flaps in each wing. The slats and the flap WTB's operate independently of each other. The central housing contains the friction disc pack which has stator and rotor discs. The central housing holds the stator discs, external splines on the torque shaft drive the rotor discs. The internal splines at each end of the torque shaft engage with the flap trans-mission system. At each end of the central housing is a hydraulic manifold which contains an annular piston. The torque shaft passes through the center of the two pistons. A solenoid valve and an electrical connector are installed on each manifold. The solenoid valves control the supply of fluid pressure to the pistons. The hydraulic supply to each WTB is as follows: - the Blue and Yellow systems supply the left flap WTB - the Blue and Green systems supply the right flap WTB. - the Blue and Green systems supply the left and right slat WTB. The two battery buses ( 701PP for system 1 and 702PP for system 2 ) supply power to the WTB solenoids through the SFCCs. This makes sure that power is available to the WTB if there is an engine power failure. Each busbar supplies one solenoid on each WTB. When the solenoids are energized, the fluid pressure moves the piston to release the spring force and puts the brake on. When the solenoids are de-energized, the fluid pressure returns through the solenoid valves and lets the brake off. Leakage of fluid past the piston seals returns through a drilled hole. If hydraulic pressure is not available to one piston, the remaining piston gives sufficient force to act against the spring to let the brake off.