landing gear anti-skid 6

antiskid purpose

Designed to allow full brake application while sending brake release orders to any wheel that decelerates too rapidly > sends hydraulic pressure back to return > bypassing the brake so we don’t apply brakes

deactivated below

10 knots

risks of a locked wheel

• Excessive tire wear

• Potential tire rupture

• Tire slipping on the rim

is antiskid AC or DC

both

components

• Wheel-speed sensors (transducers)

• Brake control valves (antiskid hydraulic valves)

• Antiskid computer (control unit)

activated when

• System is armed by pilot

• Aircraft has WOW

• Wheel spin-up has occurred

brake release order

Antiskid control valve sends hydraulic supply fluid back to return > bypass brakes

wheel speed sensors

Transmits individual wheel speed information to the antiskid control unit

control unit functions

• Generate electrical signals useable by the anti-skid hydraulic control valve

• Regulate brake pressure to prevent a skid condition

• Prevent the brakes from being applied prior to touchdown (touchdown locked-wheel protection)

touchdown

WOW > wheels spin up > wheel speed sensors generate a signal > control unit disarms locked-wheel touchdown protection circuit > control valve supplies full pressure to brakes

wheel speed greater than 20mph

antiskid system is fully active

wheel speed less than 20mph

antiskid system is inactive > pilot has full control for braking

control valves - no skid

valve allows free flow of fluid to the brake

control valves - wheel decelerates rapidly

valve closes supply and bypasses brake to avoid skid

maintenance wheel speed sensor

spin in the normal direction of rotation with the brakes and antiskid switch on > brakes should release than reapply

what is the first thing to check when troubleshooting

wheel speed sensor

maintenance antiskid control unit

circuit is divided into 2 - left & right or inboard & outboard

troubleshoot by swapping connectors

maintenance antiskid wheel control valve

check valve coil for resistance