HYDRAULIC AND LANDING GEAR SYSTEMS Author: Antonio Corrales Domínguez DPTO. DE INGENIERÍA AEROESPACIAL Y MECÁNICA DE FLUIDOS TABLE OF CONTENTS Hydraulic System Introduction to hydraulic systems Components Architecture and operation Landing Gear Introduction Components Architecture and Operation
ATA 29 Hydraulic System
INTRODUCTION TO HYDRAULIC SYSTEMS Power transfer system Pascal s law: pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid. Hydraulic power: W p S t d p Standard working pressure is 3000psi (211kg/cm 2 ) Historical background. Q ( Watts or HP) A380 => 5000 psi (352 Kg/cm 2 )!!!!!
INTRODUCTION TO HYDRAULIC SYSTEMS Hydraulic System Uses Flight Controls Ailerons Elevator Horizontal stabilizer Rudder High-lift devices Spoilers Power Plant Thrust reversers Propeller brake Landing Gear Extension/Retraction Steering Brakes Kneeling Doors and Stairs Cabin and cargo doors Ramps Stairs Electric Power Emergency generation
HYDRAULIC SYSTEM COMPONENTS Basic architecture Reservoir Pressure regulator Relief valve Pump Check valve Accumulator Selector valve Actuator
HYDRAULIC SYSTEM COMPONENTS Hydraulic Fluids MISSION 1. Transfer power 2. Lubricate moving parts 3. Seal-off packings and play 4. Transfer heat REQUIRED PROPERTIES Low compressibility Physical-chemical stability Compatible with materials Low vapour pressure Incombustible Easy to procure Good lubricating properties Hard to pollute Non foaming Low volatility Non Toxic
HYDRAULIC SYSTEM COMPONENTS Pumps Their mission is to pressurize the fluid which, moving through the hydraulic system, moves the required elements: actuators, motors, etc. Hydraulic pumps are driven by: Aircraft engines Electric motors Ram Air Turbine
HYDRAULIC SYSTEM COMPONENTS Piston Pump
HYDRAULIC SYSTEM COMPONENTS Ram Air Turbine Pump Extension mechanism Mast Hydraulic Pump Turbine
HYDRAULIC SYSTEM COMPONENTS Valves Mission Flow Control Pressure Control Selector Check Shuttle Relief Pressure reducing Discharge Back pressure Sequence Priority
HYDRAULIC SYSTEM COMPONENTS Hydraulic Fuses Their mission is to stop the flow if a leak is detected. They work by detecting: Excessive flow Severe pressure drop.
HYDRAULIC SYSTEM COMPONENTS Hydraulic Reservoir Mission: Holding hydraulic fluid. Making up for fluid lost through leakage in the system. Being a thermal regulator Being a deaerator in the fluid Types: Non-pressurized Pressurized: venturi, pressurized air, piston.
HYDRAULIC SYSTEM COMPONENTS Accumulator Missions: Minimize loading and unloading cycles in the pumps Dampen pressure oscillations Emergency power source Allows for thermal expansion of the fluid.
HYDRAULIC SYSTEM COMPONENTS Accumulators Types: Non-separated fluids. Separated: piston, diaphragm, bladder.
HYDRAULIC SYSTEM COMPONENTS Elements acting as Power Sinks Hydraulic actuators (cylinders) Electro-Hydraulic Actuators (EHA and EBHA). Hydraulic Motors
HYDRAULIC SYSTEM COMPONENTS Redundant Architecture. Airbus A340
HYDRAULIC SYSTEM COMPONENTS Normal Operation (EPD)
HYDRAULIC SYSTEM COMPONENTS Backup Operation
HYDRAULIC SYSTEM COMPONENTS Ram Air Turbine Operational
HYDRAULIC SYSTEM COMPONENTS Cockpit Indication. Airbus A340 ECAM
HYDRAULIC SYSTEM COMPONENTS Airbus A380 Architecture 2 systems: GREEN & BLUE Heat exchangers
HYDRAULIC SYSTEM COMPONENTS Airbus A380 Architecture. Heat exchangers Air / Hydraulic Fluid Fuel / Hydraulic Fluid
ATA 32 Landing Gear System
INTRODUCTION Mission of Landing Gear System: Take up contact loads originating when the aircraft is taxiing, taking off or landing. Together with other subsystems, permit control of the aircraft on ground at low speed (steering and braking). Landing Gear Arrangement: Main landing gear: withstand the main/higher loads. Auxiliary landing gear: balance the aircraft when on ground. Normally fitted with steering systems.
INTRODUCTION TO THE LANDING GEAR SYSTEM
INTRODUCTION TO THE LANDING GEAR SYSTEM
INTRODUCTION Type of Landing Gear Fixed landing gear Retractable landing gear In the wing In the fuselage In the nacelle Pod in the fuselage
INTRODUCTION
LANDING GEAR COMPOMENTS Shock Absorbers Filler valve (hydraulic fluid) Shock absorber cylinder Upper compartment (hydraulic fluid) Damping valve Piston Lower compartment (N 2 ) Filler valve (N 2 )
LANDING GEAR COMPOMENTS Wheel Fusible plug Inflation valve Heat shields Safety plug Drive blocks
LANDING GEAR COMPOMENTS Brakes Characteristics Hydraulically actuated (standard systems) Multiple-disc assembly to increase braking energy Automatic control systems Discs made out of steel, carbon or beryllium
LANDING GEAR COMPOMENTS Brakes Hydraulic system valves Brake discs Hydraulic actuators
LANDING GEAR. ARCHITECTURE AND OPERATION Braking System Subsystems Normal brakes Emergency/parking brakes Auxiliary systems Components Control pedal Proportional braking system Antiskid subsystem Cooling subsystem Temperature indicating subsystem
LANDING GEAR. ARCHITECTURE AND OPERATION Braking System. Actuating elements Brake (and rudder) Pedals Emergency/parking brake lever
LANDING GEAR. ARCHITECTURE AND OPERATION Braking System. Antiskid Subsystem
LANDING GEAR. ARCHITECTURE AND OPERATION Braking System. Automatic Centralized Braking Control
LANDING GEAR. ARCHITECTURE AND OPERATION Steering System. C295 (1) Steering wheel (2) Steering pre-selection valve (3) Anti-shimming valves (4) Selector valves (5) Accumulator (6) Pressure reducing valve (1) (4) (2) (3) (4) (6) Pressure Pressurized return Return circuit Nitrogen (5)
LANDING GEAR. ARCHITECTURE AND OPERATION Steering System. A340 and A380 A340 A380
LANDING GEAR. ARCHITECTURE AND OPERATION Landing Gear Extension and Retraction System Systems: Normal extension / retraction system. Emergency extension system (free fall).
LANDING GEAR. ARCHITECTURE AND OPERATION Landing Gear Extension and Retraction System A340 Emergency C295 Normal Emergency
LANDING GEAR. ARCHITECTURE AND OPERATION Landing Gear Extension and Retraction System
LANDING GEAR. ARCHITECTURE AND OPERATION Keeling. Ground Attitude Control System By independently controlling de length of individual shock absorbers, the aircraft s attitude can be controlled to ease loading and unloading of cargo in uneven surfaces. Additionally, the system can help the aircraft perform tighter turns with upgraded grip.
LANDING GEAR. ARCHITECTURE AND OPERATION Indicating System Parameters: Landing gear position (up/transit/down). Autobrake. Antiskid (ON/OFF). Hydraulic system pressure. Weight on wheels (WOW). Parking brake set. Tire temperature. Tire pressure.
LANDING GEAR. ARCHITECTURE AND OPERATION Indicating System
LANDING GEAR. ARCHITECTURE AND OPERATION Indicating System A340 A400M
REFERENCES CONOCIMIENTOS DE AVIÓN (4ª Edición). Antonio Esteban Oñate. Thomson Paraninfo. 1999 AIRCRAFT SYSTEMS (Third Edition). Ian Moir & Allan Seabridge. Wiley. 2008 DESIGN AND DEVELOPMENT OF AIRCRAFT SYSTEMS, AN INTRODUCTION. Ian Moir & Allan Seabridge. AIAA Educational Series. 2004. MILITARY AIRCRAFT SYSTEMS. Ian Moir & Allan Seabridge. Wiley. 2006 MANUALES DE MANTENIMIENTO C295/CN235. Airbus Military. MANUALES DE OPERACIONES C295/CN235. Airbus Military AIBUS 340 MAINTENANCE COURSE. Airbus. PILOT S HANDBOOK OF AERONAUTICAL KNOWLEDGE. FAA FLUID POWER WITH APPLICATIONS. Esposito. AIRCRAFT HYDRAULICS SYSTEMS. Krieger.
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