The TCA Anti-Skid Braking System for the F-5 is based on the mature Hydro-Aire Mark III Anti-Skid System. The Mark III Anti-Skid System utilizes modern, digital electronics control technology. Mark III systems are currently used on several fighter and trainer aircraft including the F-15 and F-18.
The system is a fully modulating, individual wheel, anti-skid control system. The anti-skid braking system provides maximum braking performance on all types of runway surfaces and improves landing performance and safety, particularly under wet or icy runway conditions. The system allows the pilot to apply full brakepedal force at all times without concern for the possibility of wheel lockup and subsequent skidding.
The Anti-Skid Braking System consists of permanently installed electrical and hydraulic system components and structural attachments.
The permanently installed Anti-Skid Braking System components include:
- Wheel Speed transducers are added with special wheel hubcaps.
- A digital Anti-Skid Electronic Control System is added
- Dual Anti-Skid Control valves are added.
- A hydraulic pressure-reducing valve is added.
- A filter is added to the hydraulic system.
- Hydraulic system plumbing is modified.
- Structural attachment fittings are added.
- Cockpit controls and displays are added/modified.
Although the minimum braked landing distance reduction is dependent upon runway conditions and pilot technique, the system can shorten the ground-roll by 15 to 20 percent on a dry, hard surface runway and in excess of 25 percent for a wet runway. The system is totally automatic; the pilot can leave the system activated at all times.
The anti-skid braking system senses impending wheel skid during braking and modulates the brake hydraulic pressure to prevent wheel lockup. If the pilot’s braking effort is less than the skid limit, normal braked deceleration is obtained and the Anti-Skid system is passive. However, if pilot-braking effort exceeds the skid limit, the Anti-Skid system activates and using wheel speed feedback to optimize the hydraulic pressure, modulates the brakes and, thus, obtains maximum braking throughout the roll.
Anti-skid is initiated on touchdown by the right main landing gear weight-on wheels switch. The wheel speed transducer prevents the brakes from being applied until the main wheels spin up to a speed sufficient for the normal anti-skid system to operate. The wheel speed transducer also prevents the main wheels from spinning down too rapidly and locking. To preclude inadvertent loss of braking at low speeds, the Anti-Skid is deactivated and reverts to the normal braking mode at speeds below approximately 15 knots. When the Anti-Skid system is turned off, the brake system reverts to the original pilot modulated, direct braking system.