Airplane Brake Systems and Safety
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Questions and Answers

What can excessive braking cause in tailwheel-type airplanes?

  • Tire blowout
  • Engine failure
  • Nose-over or ground loop (correct)
  • Loss of tire pressure
  • What is a challenge of modern high-speed jet aircraft brake systems?

  • Maintaining optimum friction
  • Applying equal brake pressure to all wheels
  • Releasing locked-up wheels
  • Knowing when one wheel begins to skid (correct)
  • What happens when the friction between the tire and runway is too great?

  • Aircraft acceleration increases
  • Tire grip increases
  • Tire slippage occurs (correct)
  • Wheel rotation rate increases
  • What is the ideal braking condition?

    <p>Applying brake pressure until the wheel starts to slip</p> Signup and view all the answers

    What feature is needed in an antiskid system to detect changes in deceleration rate?

    <p>Wheel-speed sensor</p> Signup and view all the answers

    What happens in a modern modulated antiskid system when a wheel decelerates too rapidly?

    <p>Some pressure is dumped into the system-return manifold</p> Signup and view all the answers

    What is the purpose of the auto-brake feature?

    <p>To automatically apply brakes when the system senses weight on the main wheels</p> Signup and view all the answers

    What components work together in an antiskid system without human interference?

    <p>Wheel speed sensors, anti-skid control valves, and control unit</p> Signup and view all the answers

    What is a potential consequence of heavy braking on large-diameter tires on small wheels?

    <p>Tires slipping on rims and pulling out valves</p> Signup and view all the answers

    How do multiple wheels on each side of modern high-speed jet aircraft affect brake control?

    <p>It makes it impossible to know when one wheel begins to skid</p> Signup and view all the answers

    What happens when the friction between the tire and runway slows the aircraft?

    <p>The aircraft slows down</p> Signup and view all the answers

    What is the purpose of pumping brakes in manual antiskid control?

    <p>To slow the wheel and release before it locks up</p> Signup and view all the answers

    What is the function of the control circuit in a modern modulated antiskid system?

    <p>To measure the time required for the wheel to spin back up</p> Signup and view all the answers

    What happens to the brake-return system in an antiskid system?

    <p>It retains some pressure</p> Signup and view all the answers

    What is the effect of contamination on runway surfaces on brake control?

    <p>It decreases the coefficient of friction</p> Signup and view all the answers

    What is the purpose of the auto-brake feature in conjunction with the antiskid system?

    <p>To automatically apply brakes to produce one of several pilot-selected levels of deceleration</p> Signup and view all the answers

    Study Notes

    Brake Control Concerns

    • Excessive braking can cause a nose-over or ground loop in tailwheel-type airplanes
    • Heavy braking can cause tires to slip on rims and pull out valves in large-diameter tires on small wheels

    Modern Brake Systems

    • Most modern high-speed jet aircraft have multiple wheels on each side, controlled by a single pedal
    • No way to know when one wheel begins to skid
    • Prompt corrective action needed to release locked-up wheel to prevent tire blowout and loss of control

    Brake Friction and Tire Slippage

    • Friction from brakes reduces wheel rotation rate and slows aircraft
    • Friction between tire and runway slows aircraft, but too much can cause tire to slip instead of grip
    • Slowing tire rotation rate too rapidly can cause tire to slip and lead to skid
    • Applying only enough brake pressure to cause tire to just begin to slip produces maximum deceleration rate
    • Maintaining optimum friction is difficult, as less brake pressure is needed as aircraft slows

    Contamination and Runway Conditions

    • Contamination like water, snow, or ice on runway reduces coefficient of friction between tire and runway
    • Complicates maintaining right amount of brake pressure for maximum braking without excessive tire slippage

    Manual Antiskid Control

    • Pumping brakes to slow wheel and then releasing before wheel locks up is a simple form of manual antiskid control
    • This method only works when control valves can operate very quickly

    Ideal Braking Condition

    • Applying brake pressure until wheel starts to slip, but not skid, is the ideal condition
    • However, pilot has no indication when slip is reached and continues to increase brake pressure

    Antiskid System Requirements

    • Two features needed: wheel-speed sensor to detect change in deceleration rate and valve that can release pressure before wheel gets into a skid
    • Retained pressure prevents brake-return system from pulling pressure plate all the way back, allowing brakes to reapply quickly

    Modern Modulated Antiskid System

    • Provides fastest wheel-speed recovery and minimum stopping distance on any runway surface
    • Pilots need to depress brake pedals all the way to induce maximum braking
    • If wheel decelerates too rapidly, indicating impending skid, some pressure is dumped into system-return manifold
    • Control circuit measures time required for wheel to spin back up and applies reduced pressure to brake

    Auto-Brake Feature

    • Works in conjunction with antiskid system
    • Automatically applies brakes when system senses weight on main wheels to produce one of several pilot-selected levels of deceleration
    • Pilot can override and disarm autobrake system by applying manual brakes

    Anti-Skid System Components

    • Wheel speed sensors
    • Anti-skid control valves
    • Control unit
    • These components work together without human interference to slow the aircraft without pedal input

    Brake Control Concerns

    • Excessive braking can cause nose-overs or ground loops in tailwheel-type airplanes
    • Heavy braking can lead to tire slippage on rims and valve stem pull-out in large-diameter tires on small wheels

    Modern Brake Systems

    • Modern high-speed jet aircraft typically have multiple wheels on each side, controlled by a single pedal
    • There is no way to detect when one wheel begins to skid
    • Prompt corrective action is necessary to release locked-up wheels and prevent tire blowouts and loss of control

    Brake Friction and Tire Slippage

    • Brake friction reduces wheel rotation rate, slowing the aircraft
    • Friction between the tire and runway slows the aircraft, but excessive friction can cause tire slippage instead of grip
    • Rapidly slowing tire rotation rates can cause tire slippage and lead to skids
    • Maximum deceleration rate is achieved by applying enough brake pressure to cause the tire to just begin slipping
    • Maintaining optimal friction is challenging, as less brake pressure is needed as the aircraft slows

    Contamination and Runway Conditions

    • Runway contamination (e.g., water, snow, or ice) reduces the coefficient of friction between the tire and runway
    • Contamination complicates maintaining the right amount of brake pressure for maximum braking without excessive tire slippage

    Manual Antiskid Control

    • Pumping brakes to slow the wheel and then releasing before it locks up is a simple form of manual antiskid control
    • This method only works when control valves can operate rapidly

    Ideal Braking Condition

    • The ideal braking condition is when brake pressure is applied until the wheel starts to slip, but not skid
    • However, pilots have no indication when slip is reached, and often continue to increase brake pressure

    Antiskid System Requirements

    • Two essential features are needed: wheel-speed sensors to detect changes in deceleration rates and valves that can release pressure before the wheel skids
    • Retained pressure prevents the brake-return system from pulling the pressure plate all the way back, allowing brakes to reapply quickly

    Modern Modulated Antiskid System

    • This system provides the fastest wheel-speed recovery and minimum stopping distance on any runway surface
    • Pilots must depress the brake pedals all the way to induce maximum braking
    • If the wheel decelerates too rapidly, indicating an impending skid, some pressure is dumped into the system-return manifold
    • The control circuit measures the time required for the wheel to spin back up and applies reduced pressure to the brake

    Auto-Brake Feature

    • This feature works in conjunction with the antiskid system
    • It automatically applies brakes when the system senses weight on the main wheels, producing one of several pilot-selected levels of deceleration
    • Pilots can override and disarm the autobrake system by applying manual brakes

    Anti-Skid System Components

    • Wheel speed sensors
    • Anti-skid control valves
    • Control unit
    • These components work together without human interference to slow the aircraft without pedal input

    Brake Control Concerns

    • Excessive braking can cause nose-overs or ground loops in tailwheel-type airplanes
    • Heavy braking can lead to tire slippage on rims and valve stem pull-out in large-diameter tires on small wheels

    Modern Brake Systems

    • Modern high-speed jet aircraft typically have multiple wheels on each side, controlled by a single pedal
    • There is no way to detect when one wheel begins to skid
    • Prompt corrective action is necessary to release locked-up wheels and prevent tire blowouts and loss of control

    Brake Friction and Tire Slippage

    • Brake friction reduces wheel rotation rate, slowing the aircraft
    • Friction between the tire and runway slows the aircraft, but excessive friction can cause tire slippage instead of grip
    • Rapidly slowing tire rotation rates can cause tire slippage and lead to skids
    • Maximum deceleration rate is achieved by applying enough brake pressure to cause the tire to just begin slipping
    • Maintaining optimal friction is challenging, as less brake pressure is needed as the aircraft slows

    Contamination and Runway Conditions

    • Runway contamination (e.g., water, snow, or ice) reduces the coefficient of friction between the tire and runway
    • Contamination complicates maintaining the right amount of brake pressure for maximum braking without excessive tire slippage

    Manual Antiskid Control

    • Pumping brakes to slow the wheel and then releasing before it locks up is a simple form of manual antiskid control
    • This method only works when control valves can operate rapidly

    Ideal Braking Condition

    • The ideal braking condition is when brake pressure is applied until the wheel starts to slip, but not skid
    • However, pilots have no indication when slip is reached, and often continue to increase brake pressure

    Antiskid System Requirements

    • Two essential features are needed: wheel-speed sensors to detect changes in deceleration rates and valves that can release pressure before the wheel skids
    • Retained pressure prevents the brake-return system from pulling the pressure plate all the way back, allowing brakes to reapply quickly

    Modern Modulated Antiskid System

    • This system provides the fastest wheel-speed recovery and minimum stopping distance on any runway surface
    • Pilots must depress the brake pedals all the way to induce maximum braking
    • If the wheel decelerates too rapidly, indicating an impending skid, some pressure is dumped into the system-return manifold
    • The control circuit measures the time required for the wheel to spin back up and applies reduced pressure to the brake

    Auto-Brake Feature

    • This feature works in conjunction with the antiskid system
    • It automatically applies brakes when the system senses weight on the main wheels, producing one of several pilot-selected levels of deceleration
    • Pilots can override and disarm the autobrake system by applying manual brakes

    Anti-Skid System Components

    • Wheel speed sensors
    • Anti-skid control valves
    • Control unit
    • These components work together without human interference to slow the aircraft without pedal input

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    Description

    Learn about the concerns and modern systems of airplane brake controls, including excessive braking risks and corrective actions to prevent tire blowouts and loss of control.

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