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B737 NG Landing gear

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B737NG Landing Gear overview

  • could I have acopy of this slide ....yousef.bedour@jordanaviation.jo
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  • What is the role of temperature Sensor in the landing gear and braking system?
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  • BUENAS TARDES, VIVOEN MÉXICO TENGO UN HERMANO AL CUAL LE SERVIRÍA TENER ESTA PRESENTACIÓN, ÉL IMPARTE CLASES PARA CAPACITAR A JOVENES EN EL ÁREA DE MANTENIMIENTO AERONÁUTICO, POR LO CUAL LE SOLICITO AMABLEMENTE SI ME PUDIESE COMPARTIRLA PARA ENTREGARSELA, UN CORDIAL SALUDO.
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  • great!!!!
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  • Hello Sir, I'm from The Maldives. I have a good friend of mine who's a fire fighter at Ibrahim Nasir International Airport. He wanted to get some information on modern aircraft landing gear system, and asked me to check online. I've found some videos but not with that much detail.

    So, I was wondering whether you allow my to download this slide, so that I can help out my friend.

    My details:
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    Abdhulla Neevin Ahmed
    neevin2009@gmail.com

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    Neevin
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B737 NG Landing gear

  1. 1. B 737 NG Ground School. See the aircraft study guide at www.theorycentre.com The information contained here is for training purposes only. It is of a general nature it is unamended and does not relate to any individual aircraft. The FCOM must be consulted for up to date information on any particular aircraft.
  2. 2. LANDING GEAR
  3. 3. Introduction The airplane has two main landing gear and a single nose gear. Each main gear is a conventional two–wheel landing gear unit. The nose gear is a conventional steerable two–wheel unit. Hydraulic power for retraction, extension, and nose wheel steering is normally supplied by hydraulic system A. A manual landing gear extension system and an alternate source of hydraulic power for nose wheel steering are also provided. The normal brake system is powered by hydraulic system B. The alternate brake system is powered by hydraulic system A. Antiskid protection is provided on both brake systems, but the autobrake system is available only with the normal brake system.
  4. 4. System A Powers. Landing Gear extension and retraction (Normal). Nose Wheel Steering . ALTERNATE BRAKING.
  5. 5. System B Powers. Normal Braking Alternate Nose Wheel Steering. Alternate RETRACTION ONLY.
  6. 6. Landing Gear Extension When the LANDING GEAR lever is moved to DN, hydraulic system A pressure is used to release the uplocks. The landing gear extends by hydraulic pressure, gravity and air loads. Over centre mechanical and hydraulic locks hold the gear at full extension. The nose wheel doors remain open when the gear is down.
  7. 7. Normal Operation : Hydraulic system A. DOWN selection puts HYD pressure to down lines.
  8. 8. Landing Gear Retraction When the LANDING GEAR lever is moved to UP, the landing gear begins to retract. During retraction, the brakes automatically stop rotation of the main gear wheels. After retraction, the main gear are held in place by mechanical uplocks. Rubber seals and oversized hubcaps complete the fairing of the outboard wheels. The nose wheels retract forward into the wheel well and nose wheel rotation is stopped by snubbers. The nose gear is held in place by an over center lock and enclosed by doors which are mechanically linked to the gear.
  9. 9. Normal Operation : Hydraulic system A. DOWN selection puts HYD pressure to down lines. UP Hydraulic Pressure to UP lines. .
  10. 10. During retraction, the brakes automatically stop rotation of the main gear wheels. Nose wheel rotation is stopped by snubbers
  11. 11. Hydraulic pressure is removed from the landing gear system with the LANDING GEAR lever in the OFF position.
  12. 12. Normal Operation : Hydraulic system A. DOWN selection puts HYD pressure to down lines. UP Hydraulic Pressure to UP lines. OFF REMOVES PRESSURE.
  13. 13. EXTEND 270 Knots or M0.82. (Air loads on the nose gear.) RETRACT 235 Knots. (Air loads) EXTENDED 320 Knots or M0.82 OPERATING LIMITATIONS.
  14. 14. MAIN LANDING GEAR ACTUATION Down and locked Up lock Down lock Up lock roller Actuator Locked up Transit
  15. 15. NOSE LANDING GEAR ACTUATION FWD Down and locked Actuator Lock Mechanism Lock Actuator Transit Locked up
  16. 16. Landing Gear Operation The landing gear are normally controlled by the LANDING GEAR lever. On the ground, a landing gear lever lock, prevents the LANDING GEAR lever from moving to the up position. An override trigger in the lever may be used to bypass the landing gear lever lock. In flight, the air/ground system energizes a solenoid which opens the lever lock.
  17. 17. Landing Gear Lever Lock Mechanism In Ground mode. The landing gear lever is locked in the down position. Landing gear lever lock pawl (Lever lock position.) Landing gear lever unlock solenoid
  18. 18. Landing Gear Lever Lock Mechanism In Air mode the Lever lock solenoid is energised and the lever is unlocked. The lever must be pulled out before it can be moved to UP Locked Ground mode. Unlocked Air mode.
  19. 19. Landing Gear Lever Lock Mechanism In Air mode the Lever lock solenoid is energised and the lever is unlocked. The lever must be pulled out before it can be moved to UP Unlocked Air mode. Unlocked and lever pulled out.
  20. 20. Landing Gear Lever Lock Mechanism If the lever lock fails to unlock the Lever Lock Override Trigger may be used to manually unlock the lever. Solenoid failed. Locking pawl lock position Landing gear lever pulled out and lock release trigger pulled
  21. 21. Use of the landing gear override trigger must be strictly in accordance with the QRH. This will be found in the Unannunciated section (No lights or other indications) There are 3 reasons why this may have happened. 1. The unlocking solenoid has failed. This is simple and the gear can be retracted using the override trigger. 2. A failure of the Air/Ground sensing system. This means that many aircraft systems are still in the ground mode and will not correctly function in flight. The aircraft must be landed. 3. The Ground spoiler bypass valve failed to close at takeoff. (mechanical linkage on the right main gear.) This means that use of the speed brakes in flight could potentially cause the ground spoilers to deploy. Items 2 and 3 require a landing. Follow the QRH procedures to identify the failure.
  22. 22. The landing gear position indicating and warning system shows landing gear position in the flight compartment. It also warns the pilots when the landing gear is not down for a landing. Inputs The landing gear position indicating and warning system uses these proximity sensors to supply landing gear position data to the proximity switch electronics unit (PSEU): Left and right main gear up and locked sensors (2 on each up lock) Left and right main gear down lock sensors (2 on each down lock) Nose gear up/down lock sensors (2 the same sensors are used Up and Down) Nose gear down sensors (2). The PSEU processes all of the inputs and sends signals to the landing gear position lights and the aural warning module. Three red landing gear position lights come on when the landing gear moves during extension and retraction and during the gear not down warning. When the landing gear extends to the down and locked position, three primary and three auxiliary green landing gear position lights come on. The primary and secondary indicators use independent sensors. LANDING GEAR POSITION INDICATING
  23. 23. AFT OVERHEAD PANEL Landing Gear Indicator Lights (overhead) Illuminated (green) – related gear down and locked. Note: Landing gear warning horn is deactivated with all gear down and locked. Note: Landing gear is down and locked as long as one green landing gear indicator light (centre panel or overhead panel) for each gear is illuminated. Extinguished – landing gear is not down and locked. Primary indicators Auxiliary indicators.
  24. 24. Landing Gear Manual Extension If hydraulic system A pressure is lost, the manual extension system provides another means of landing gear extension. Manual gear releases on the flight deck are used to release uplocks that allow the gear to free–fall to the down and locked position. The forces that pull the gear down are gravity and air loads. With the manual extension access door open: • manual landing gear extension is possible with the LANDING GEAR lever in any position. The lever should be in the OFF position to ensure that no hydraulic lock exists. • normal landing gear extension is possible if hydraulic system A pressure is available. • landing gear retraction is disabled a switch on the access door electrically depressurises the up lines to ensure the gear is free to lower.
  25. 25. Alternate Lowering. If Hydraulic System A is failed then the gear must be extended Manually.
  26. 26. Alternate Lowering. • Maximum airspeed is 270 Knots • Nose wheel extension assisted by air load • Allow 15 seconds for gear to extend & lock • Gear Lever should be selected OFF • Recommended for F/O to extend.
  27. 27. Alternate Lowering. Manual Gear Extension handles • Located on the floor aft of, & between, the FOs seat & the centre console • Length of cable is 60 cm First part of travel is free play only. • Friction through last portion of travel actually releases the up locks. • Manual Extension Access Door • With the door open, NORMAL Extension is Possible. (With SYS A) • RETRACTION IS NOT POSSIBLE • Door position switch sets selector valve to bypass. Up lines are open to return system only. This ensures no hydraulic lock during manual extension. • If the gear will not retract check that the access door is properly closed.
  28. 28. SYS A SYS B NORMAL ALTERNATE N2 < 50% LANDING GEAR TRANSFER UNIT B system supplies the volume of hydraulic fluid required to raise the landing gear at the normal rate when all of the following conditions exist: • airborne • No. 1 engine RPM drops below a limit value • LANDING GEAR lever is positioned UP • either main landing gear is not up and locked.
  29. 29. SYS A SYS B NORMAL ALTERNATE N2 < 50% LANDING GEAR TRANSFER UNIT B system supplies the volume of hydraulic fluid required to raise the landing gear at the normal rate when all of the following conditions exist: • airborne • No. 1 engine RPM drops below a limit value • LANDING GEAR lever is positioned UP • either main landing gear is not up and locked. This allows rapid gear retraction if an engine failure occurs between V1 and gear up.
  30. 30. fran·gi·ble adj.Capable of being broken; breakable. If a main landing gear tire is damaged during takeoff, it is possible that braking of the main gear wheels during retraction may be affected. A spinning tire with a loose tread must be stopped prior to entering the wheel well or it can cause damage to wheel well components. When a spinning tire with loose tread impacts a fitting in the wheel well ring opening, that gear stops retracting and free falls back to the down position. The affected gear cannot be retracted until the fitting is replaced. Frangible Fitting Hydraulic A system pressure Volume fuse Frangible fitting Main gear retract pressure If the frangible fitting breaks the volume fuse seals the line after a measured volume of fluid has passed. This preserves the remainder of the system fluid.
  31. 31. FRANGIBLE FITTING
  32. 32. Air/Ground System In flight and ground operation of various airplane systems are controlled by the air/ground system. The system receives air/ground logic signals from six sensors, two on each landing gear. These signals are used to configure the airplane systems to the appropriate air or ground status. The air/ground system supplies air/ground discrete signals to many airplane systems. The proximity switch electronics unit (PSEU) is a component of the air/ground system. Many airplane systems send signals to the PSEU through position sensors and switches. The PSEU also controls the air/ground relays.
  33. 33. Proximity Switch Electronic Unit (PSEU) The PSEU monitors the following systems: • takeoff configuration warnings • landing configurations warnings • landing gear • air/ground sensing. The PSEU, its sensors, and its input signals are monitored for internal faults. When designated faults are detected, a PSEU light on the aft overhead panel illuminates, and the OVERHEAD system annunciator light and MASTER CAUTION lights illuminate. The PSEU light, OVERHEAD system annunciator and Master Caution illuminate automatically for simple faults, but only after a landing. The PSEU light extinguishes when a parking brake is set or when both engines are turned off. The PSEU light is inhibited: • in flight • when the thrust levers are advanced toward takeoff power • for 30 seconds after landing. Some aircraft the PSEU light may illuminate during recall. In this case, with a simple fault, resetting the MASTER CAUTION system extinguishes the PSEU light.
  34. 34. A proximity sensor is an electronic sensor capable of detecting the presence of nearby objects without physical contact. It emits an electromagnetic field and then looks for changes in the return signal or field. The object that is being sensed is the proximity sensor's target. An inductive proximity sensor requires a metal target. Proximity sensors have a long functional life and high reliability due to the absence of mechanical parts and the lack of physical contact between the sensor and the target. The sensor normally does not move it is mounted to the aircraft or component. The target moves close and the sensor sends a NEAR signal to the PSEU or the target moves away from the sensor and the sensor send a FAR signal. These are the only 2 sensing conditions. Typical aircraft installation. 2 sensors channel A &B Moving steel target Near or Far.
  35. 35. MAIN GEAR AIR GROUND SENSORS Sensors Amber. Targets Green Weight on wheels Near Ground mode Weight off wheels Far Air mode.
  36. 36. Nose Wheel Steering Nose wheel steering is available when the nose gear is in the down position and compressed by weight of the airplane. Positioning the landing gear control lever to down makes system A hydraulic pressure available to the steering metering valve. Alternate nose wheel steering can be activated to provide system B pressure to the nose wheels when the NOSE WHEEL STEERING switch is placed to ALT, normal quantity is in the system B reservoir, and the airplane is on the ground. In the event of a hydraulic leak downstream of the Landing Gear Transfer Unit resulting in a loss of hydraulic system B fluid in the reservoir, a sensor closes the Landing Gear Transfer Valve and alternate steering will be lost. Primary steering is controlled through the nose wheel steering wheel. Limited steering control is available through the rudder pedals. A pointer on the nose steering wheel assembly shows nose wheel steering position relative to the neutral setting. Rudder pedal steering is deactivated as the nose gear strut extends. A lockout pin may be installed in the towing lever to depressurize nose wheel steering. This allows airplane pushback or towing without depressurizing the hydraulic systems.
  37. 37. Steering pointer centred Full right indication
  38. 38. Steering lock out pin fitted
  39. 39. Simplified Nose Wheel Steering System Diagram. Captains Steering tiller FO’s Steering tiller (Option) Rudder pedal input Nose gear shock strut inner cylinder Push pull actuators Steering input summing lever Steering metering valve Steering shut off valve Landing gear transfer valve System A normal System B Altn
  40. 40. Steering inputs are from the steering wheels or the rudder pedals. When you move the captain or first officer steering wheel full travel, the nose wheels turn a maximum of 78 degrees in the left or right direction. When you move the rudder pedals full travel on the ground, the nose wheels turn a maximum of 7 degrees in the left or right direction. Steering inputs from the steering wheels or rudder pedals go to the metering valve through a cable loop and summing mechanism. 78⁰ Tiller 7⁰ Pedals Tail turning radius 74.9 feet 22.8 Metres Wing tip turning radius 72.1 feet 22.0 Metres Turning radius for -800. 600, 700 and 900 differ.
  41. 41. Red line on the door indicates the maximum steering angle for the tow bar. 78⁰ limit.
  42. 42. SYS A SYS B NORMAL ALTERNATE Nose Wheel Steering Alternate nose wheel steering can be activated to provide system B pressure to the nose wheels when the NOSE WHEEL STEERING switch is placed to ALT,
  43. 43. Alternate Nose wheel steering selector switch.
  44. 44. SYS A SYS B NORMAL ALTERNATE GUARDED NORMAL. HYD SYS A. ALT. HYD SYS B NOSE WHEEL STEERING SW. Nose Wheel Steering Alternate nose wheel steering can be activated to provide system B pressure to the nose wheels when the NOSE WHEEL STEERING switch is placed to ALT,
  45. 45. SYS A SYS B NORMAL ALTERNATE GUARDED NORMAL. HYD SYS A. ALT. HYD SYS B NOSE WHEEL STEERING SW. Requires: Switch to Alternate. Sys B Reservoir quantity Normal. More than 21% in the reservoir. This protects B system if there is a leak in the NWS system. Nose Gear AIR/Ground SYS Ground mode. Then Landing Gear transfer unit allows SYS B Pressure to Steering actuator.
  46. 46. If the manual gear extension door is open is it possible to retract the gear?
  47. 47. If the manual gear extension door is open is it possible to retract the gear? Normal gear extension is possible retraction is not possible. landing gear retraction is disabled a switch on the access door electrically depressurises the up lines to ensure the gear is free to lower.
  48. 48. The air/ground sensing system receives logic signals from.
  49. 49. The air/ground sensing system receives logic signals from. Two proximity sensors on each gear. Air/Ground System In flight and ground operation of various airplane systems are controlled by the air/ground system. The system receives air/ground logic signals from six sensors, two on each landing gear.
  50. 50. Located on the Aft Overhead Panel. Independent Down Locked Indication. Is the gear down and locked?
  51. 51. Located on the Aft Overhead Panel. Independent Down Locked Indication. Is the gear down and locked? YES there is one green light for each gear. A green light cannot show if the gear is not locked down. The primary channel is showing a right gear red light because that channel is not detecting the down locked sensor.
  52. 52. If the nose gear steering lock out pin is not installed during pushback what is it necessary to do? a. Select hydraulic system B pumps OFF. b. Keep your feet clear of the rudder pedals to prevent damage to the steering system. c. Select hydraulic system A pumps OFF. d. Select all hydraulic pumps OFF.
  53. 53. If the nose gear steering lock out pin is not installed during pushback what is it necessary do? a. Select hydraulic system B pumps OFF. b. Keep your feet clear of the rudder pedals to prevent damage to the steering system. c. Select hydraulic system A pumps OFF. d. Select all hydraulic pumps OFF. Positioning the landing gear control lever to down makes system A hydraulic pressure available to the steering metering valve.
  54. 54. Impact frangible fittings on the rim of each main wheel well are intended to?
  55. 55. B737 Tire speed limit = 225 MPH / 195 kt. Tyre failure at 120 MPH!
  56. 56. fran·gi·ble adj.Capable of being broken; breakable. If a main landing gear tire is damaged during takeoff, it is possible that braking of the main gear wheels during retraction may be affected. A spinning tire with a loose tread must be stopped prior to entering the wheel well or it can cause damage to wheel well components. When a spinning tire with loose tread impacts a fitting in the wheel well ring opening, that gear stops retracting and free falls back to the down position. The affected gear cannot be retracted until the fitting is replaced. Frangible Fitting Hydraulic A system pressure Volume fuse Frangible fitting Main gear retract pressure If the frangible fitting breaks the volume fuse seals the line after a measured volume of fluid has passed. This preserves the remainder of the system fluid.
  57. 57. Brake System Each main gear wheel has a multi–disc hydraulic powered brake. The brake pedals provide independent control of the left and right brakes. The nose wheels have no brakes. The brake system includes: • normal brake system • alternate brake system • brake accumulator • antiskid protection • autobrake system • parking brake Optional • brake temperature indication
  58. 58. Multi disc brake assembly Hydraulic pistons act on pressure plate to apply brakes Springs in the adjuster pull the pressure plate back to release the brakes
  59. 59. Hydraulic Piston Pressure plate Wear pin Available wear remaining with Brakes ON Automatic adjuster and return spring
  60. 60. Brake Systems • There are three brake systems • Normal Hydraulic system B. Brake metering valves toe operated from rudder pedals. Adjust system pressure more force applied on pedals higher brake Pressure.
  61. 61. Brake Systems Auto brake control module is an electronic Metering valve. Anti skid valves adjust the brake pressure To each wheel to prevent wheel locking.
  62. 62. Brake Systems Alternate Hydraulic system A. Automatically selected if System B is low pressure Alternate brake metering valves Slaved together with normal metering Valves. Adjust A system hydraulic Pressure according to force applied to The brake pedal. Alternate anti skid valves. One for each wheel pair on an axle. Slightly less efficient and greater breaking distance required.
  63. 63. Gas N2 Pre Charge is 1,000 psi Hydraulic System zero pressure. Hydraulic Accumulator A floating separator piston keeps the hydraulic fluid and Nitrogen gas separated in the accumulator.
  64. 64. Gas N2 Pre Charge is 1,000 psi Hydraulic System zero pressure. B737 Cockpit Pressure Gage Shows Nitrogen gas pressure in the Brake accumulator. Hydraulic Accumulator
  65. 65. Gas N2 Pre Charge is 1,000 psi Hydraulic System zero pressure. Hydraulic System Pressure 3,000 psi Gas Pressure 3,000 psi Energy stored in the nitrogen gas. B737 Cockpit Pressure Gage Hydraulic Accumulator
  66. 66. Brake Systems • Accumulator The brake accumulator is pressurized by hydraulic system B. If both normal and alternate brake system pressure is lost, trapped hydraulic pressure in the brake accumulator can still provide several braking applications or parking brake application.
  67. 67. Brake Systems Accumulator brakes • System B hydraulics pressurises the accumulator to 3,000 psi - accumulator has a 1,000 psi N2 pre-charge Brake Pressure Indicator Brake Accumulator (behind bulkhead) Pressure Gauge AFT WALL (main wheel well)
  68. 68. Brake Systems Accumulator brakes • System B hydraulics pressurises the accumulator to 3,000 psi - accumulator has a 1,000 psi N2 pre-charge Brake Pressure Indicator OLD 737 Accumulator is In the Wheel well. NG moved to the Wing to body fairing aft of wheel well Brake Accumulator (behind bulkhead) Brake pressure transducer
  69. 69. Brake pedal installation Cockpit
  70. 70. Main and Alternate Brake metering valves Main wheel well
  71. 71. WHEEL SPEED TRANSDUCERS Electrical generator. As the wheel turns faster more volts are produced
  72. 72. Antiskid Protection Antiskid protection is provided in the normal and alternate brake systems. The normal brake hydraulic system provides each main gear wheel with individual antiskid protection. When the system detects a skid, the associated antiskid valve reduces brake pressure until skidding stops. The alternate brake hydraulic system works similar to the normal system however antiskid protection is applied to main gear wheel pairs instead of individual wheels. Both normal and alternate brake systems provide skid, locked wheel, touchdown and hydroplane protection. Antiskid protection is available even with loss of both hydraulic systems.
  73. 73. Wheel Speed Transducers Antiskid System The antiskid system monitors wheel deceleration and controls the brake metered pressure to prevent skid conditions. These are the antiskid functions: * Skid control operates at more than eight knots to control each wheel deceleration during normal antiskid and both wheels on each main landing gear during alternate antiskid * Locked wheel protection compares wheel speeds more than 25 knots difference between the two inboard or the two outboard wheels and releases brake pressure from the slower wheel
  74. 74. Wheel Speed Transducers Antiskid System The antiskid system monitors wheel deceleration and controls the brake metered pressure to prevent skid conditions. These are the antiskid functions: * Touchdown protection prevents wheel brake application on wheels 2 and 4 when the airplane is in the air
  75. 75. Wheel Speed Transducers ADIRU Antiskid System The antiskid system monitors wheel deceleration and controls the brake metered pressure to prevent skid conditions. These are the antiskid functions: * Hydroplane protection decreases wheel brake pressure to wheel 1 and 3 when ground speed is more than wheel speed uses the ADIRU ground speed.
  76. 76. Antiskid System The antiskid system monitors wheel deceleration and controls the brake metered pressure to prevent skid conditions. These are the antiskid functions: * Gear retract inhibit prevents the alternate anti skid system from operation during normal landing gear retraction. This ensures the wheels are stopped during retraction.
  77. 77. Brake Systems Alternate brakes Source select valve • Uses system A hydraulics - automatically selected when system B hydraulic pressure is low (no crew action required) B System Pressure keeps Alternate Source selector closed. Hydraulic system B pressure System A pressure
  78. 78. Brake Systems Alternate brakes Source select valve • Uses system A hydraulics - automatically selected when system B hydraulic pressure is low (no crew action required) B System Pressure low system A moves the piston and selects alternate brakes. Hydraulic system B low pressure System A pressure Alternate Brake metering valves
  79. 79. System A UP LINE PRESSURE Alternate Brake Metering Valves During retraction, the brakes automatically stop rotation of the main gear wheels. Gear retract inhibit prevents the alternate anitskid system from operation during normal landing gear retraction. This ensures the wheels are stopped during retraction. Alternate source select valve
  80. 80. Brake Systems • If system B hydraulics fails, brake accumulator pressure is isolated from the system by the accumulator isolation valve
  81. 81. Brake Systems • If system B hydraulics fails, brake accumulator pressure is isolated from the system by the accumulator isolation valve • If system A & B hydraulics fail, accumulator pressure moves the isolation valve to send pressure to normal system • Antiskid operates normally - expect about 8 full brake applications • Auto Brake is not available
  82. 82. NORMAL BRAKES SYSTEM AAND B WORKING
  83. 83. ALTERNATE BRAKING WITH SYSTEM B FAILED.
  84. 84. ACCUMULATOR BRAKING SYSTEM A & B FAILED.
  85. 85. Brake Systems Brake pressure indications • Normal system pressure = 3,000 psi • Nitrogen Gas Pre Charge is 1,000 PSI • If brake pressure indicates 0 psi then the pre-charge is lost • if system A or B hydraulics is normal then expect normal braking, Parking brake will NOT HOLD WITH PUMPS OFF!
  86. 86. Brake Systems Brake pressure indications • Normal system pressure = 3,000 psi • Nitrogen Gas Pre Charge is 1,000 PSI • If brake pressure indicates 0 psi then the pre-charge is lost • if system A or B hydraulics is normal then expect normal braking, Parking brake will NOT HOLD WITH PUMPS OFF!
  87. 87. Auto brake System The auto brake system uses hydraulic system B pressure to provide maximum deceleration for rejected takeoff and automatic braking at preselected deceleration rates immediately after touchdown. The system operates only when the normal brake system is functioning. Antiskid system protection is provided during auto brake operation.
  88. 88. Rejected Takeoff (RTO) The RTO mode can be selected only when on the ground. Upon selection, the AUTO BRAKE DISARM light illuminates for one to two seconds and then extinguishes, indicating that an automatic self–test has been successfully accomplished. To arm the RTO mode prior to takeoff the following conditions must exist: • airplane on the ground • antiskid and auto brake systems operational • AUTO BRAKE select switch positioned to RTO • wheel speed less than 60 knots • forward thrust levers positioned to IDLE. With RTO selected, if the takeoff is rejected prior to wheel speed reaching 90 knots auto braking is not initiated, the AUTO BRAKE DISARM light does not illuminate and the RTO auto brake function remains armed. If the takeoff is rejected after reaching a wheel speed of 90 knots, maximum braking is applied automatically when the forward thrust levers are retarded to IDLE. The RTO mode is automatically disarmed when both air/ground systems indicate the air mode. The AUTO BRAKE DISARM light does not illuminate and the AUTO BRAKE select switch remains in the RTO position. To reset or manually disarm the auto brake system, position the selector to OFF. If a landing is made with RTO selected (AUTO BRAKE select switch not cycled through OFF), no automatic braking action occurs and the AUTO BRAKE DISARM light illuminates two seconds after touchdown.
  89. 89. Auto Brake System • Select RTO on ground before departure; Conducts self test & initiates system if: • Wheel speed is 60 kts • Forward thrust levers are at idle • RTO braking (3,000 psi) is activated when: • Wheel speed is 90 kts • Forward thrust levers are retarded • Aircraft is on the ground (disarmed in air mode) • If take-off is rejected below 90 kts then: • No braking action occurs • The AUTO BRAKE DISARM light does not illuminate Brakes stay Armed.
  90. 90. Landing When a landing auto brake selection is made, the system performs a turn– on– self–test. If the turn–on–self–test is not successful, the AUTO BRAKE DISARM light illuminates and the auto brake system does not arm. Four levels of deceleration can be selected for landing. However, on dry runways, the maximum auto brake deceleration rate in the landing mode is less than that produced by full pedal braking. After landing, auto brake application begins when: • both forward thrust levers are retarded to IDLE • the main wheels spin–up. One wheel on each main gear above 60 knots. Note: Landing auto brake settings may be selected after touchdown prior to decelerating through 30 kts of ground speed. Braking initiates immediately if the above conditions are met. To maintain the selected landing deceleration rate, auto brake pressure is reduced as other controls, such as thrust reversers and spoilers, contribute to total deceleration. The deceleration level can be changed (without disarming the system) by rotating the selector. The auto brake system brings the airplane to a complete stop unless the braking is terminated by the pilot by selecting the auto brake switch to OFF, Increasing the metered brake pressure by pressing the brake pedals or advancing the thrust levers above idle.
  91. 91. Auto Brake System Auto Brake settings & deceleration rates for landing are: • 1 = 4 ft/sec (Max 1,285 psi) • 2 = 5 ft/sec (Max 1,500 psi) • 3 = 7.2 ft/sec (Max 2,000 psi) • Max = 14 ft/sec 80 kts & 12 ft/sec 80 kts (3,000 psi) These are Deceleration rates: If Reverse thrust and or spoilers are used Pressures will be reduced to maintain the deceleration rate! NOTE; RTO and MAX auto brake are similar. The main difference being that RTO is not a selected deceleration rate it is maximum braking.
  92. 92. AUTO BRAKE DISARM Light Illuminated (amber) – • SPEED BRAKE lever moved to down detent during RTO or landing • manual brakes applied during RTO or landing • thrust lever(s) advanced during RTO or landing (except during first 3 seconds after touchdown for landing) • landing made with RTO selected illuminates 2 seconds after main wheel spin up. • RTO mode selected on ground • illuminates for one to two seconds during system self test then extinguishes • a malfunction exists in automatic braking system. Extinguished – • AUTO BRAKE select switch set to OFF • auto brake armed.
  93. 93. Antiskid Inoperative (ANTISKID INOP) Light Illuminated (amber) – a system fault is detected by antiskid monitoring system. Extinguished – antiskid system operating normally.
  94. 94. Antiskid Inoperative (ANTISKID INOP) Light Illuminated (amber) – a system fault is detected by antiskid monitoring system. Extinguished – antiskid system operating normally. Landing Gear Limitations Operation with assumed temperature reduced takeoff thrust is not permitted with anti-skid inoperative. Non–AFM Operational Information Note: The following items are not AFM limitations, but are provided for flight crew information. Do not apply brakes until after touchdown.
  95. 95. AUTO BRAKE REQUIRES ANTI SKID! ANTI SKID WILL WORK WITHOUT AUTO BRAKE.
  96. 96. AUTO BRAKE REQUIRES ANTI SKID! ANTI SKID WILL WORK WITHOUT AUTO BRAKE. IF ANTI SKID IS INOP AUTO BRAKE IS NOT AVAILABLE!
  97. 97. Parking Brake The parking brake can be set with either A or B hydraulic systems pressurized. If A and B hydraulic systems are not pressurized, parking brake pressure is maintained by the brake accumulator. Accumulator pressure is shown on the HYD BRAKE PRESS indicator. The parking brake is set by depressing both brake pedals fully, while simultaneously pulling the PARKING BRAKE lever up. This mechanically latches the pedals in the depressed position and commands the parking brake valve to close. The parking brake is released by depressing the pedals until the PARKING BRAKE lever releases. A fault in the parking brake system may cause the ANTISKID INOP light to illuminate. This is because the Normal anti skid system releases pressure through the park brake valve. If the valve is not fully open anti skid may not be able to control brake pressure correctly. Parking Brake lever UP Brakes ON Red light indicates Parking brake valve is closed.
  98. 98. The TAKEOFF CONFIG lights (option) illuminate and the takeoff configuration warning horn sounds if either forward thrust lever is advanced for takeoff with the parking brake set. Main Panel F/O Main panel Captain
  99. 99. Brake Temperature (BRAKE TEMP) Light Illuminated (amber) - • temperature of one or more brakes exceed 4.9 • extinguishes when a hot brake condition is no longer indicated on the display unit. Option on F/O’s main panel Option SYS page lower DU Brake Temperature Indicates a relative value of wheel brake temperature • values range from 0.0 to 9.9 • displayed (white) - normal brake temperature range, 0.0 to 4.9 • displayed (amber) - high brake temperature, exceeds 4.9.
  100. 100. Brake Symbol Displayed (blank) - indicates any brake less than 2.5. Displayed (solid white) - indicates the hottest brake on each main gear truck, within the range of 2.5 to 4.9. Displayed (solid amber) - indicates brake overheat condition on each wheel within the range of 5.0 to 9.9. Symbol remains until value is less than 3.5.
  101. 101. How can you verify that the parking brake is set?
  102. 102. How can you verify that the parking brake is set? Parking brake lever up and parking brake light illuminated. Lever Up indicates pedals are locked in On position Light indicates only that the Parking brake valve is closed.
  103. 103. How can you verify that the parking brake is set? 1,000 PSI is gas pre charge only! Full charge should give a brake hold over time of 8 Hours. There must be a pressure of more than 1,000 psi or the brakes will not be ON.
  104. 104. How can you verify that the parking brake is set? A fault in the parking brake system may cause the ANTISKID INOP light to illuminate.
  105. 105. The END of Landing Gear Now Take the test at www.theorycentre.com Or contact us for further information info@theorycentre.com

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