How the Landing Gear of Boeing 787 Airplane Works: A Detailed Guide

The Boeing 787 Dreamliner’s landing gear system is a complex and highly reliability-focused design that incorporates a combination of hydraulics, mechanics, and electronics to ensure safe and efficient operation. The system is designed to support the aircraft’s weight, absorb the shock of landing, and provide a stable platform for taxiing and braking.

Overall System Architecture

The 787’s landing gear system consists of three main components:

1. Main Landing Gear (MLG): Located under the wings, the MLG consists of two legs, each with a wheel and brake assembly. The MLG is designed to support the majority of the aircraft’s weight during landing and taxiing.

2. Nose Landing Gear (NLG): Located under the cockpit, the NLG consists of a single leg with a wheel and steering assembly. The NLG is designed to support the aircraft’s nose section and provide steering during taxiing.

3. Landing Gear Control and Indication System: This system consists of electronic and mechanical components that control the extension and retraction of the landing gear, as well as provide indication of the gear’s position to the flight crew.

Hydraulic System

The 787’s landing gear system uses a hydraulic system to extend and retract the MLG and NLG. The hydraulic system consists of:

1. Hydraulic Power Generation: The 787 has three independent hydraulic systems, each powered by an electric motor-driven pump. These pumps generate hydraulic pressure, which is then distributed to the landing gear system.

2. Hydraulic Actuators: The MLG and NLG are equipped with hydraulic actuators, which are used to extend and retract the gear. The actuators are controlled by the hydraulic system and are designed to provide the necessary force and speed to extend and retract the gear.

3. Hydraulic Valves: The hydraulic system uses valves to control the flow of hydraulic fluid to the actuators. The valves are electronically controlled and are designed to provide precise control over the hydraulic system.

Mechanical System

The mechanical system of the 787’s landing gear includes:

1. Gear Legs: The MLG and NLG are equipped with gear legs, which are designed to absorb the shock of landing and provide a stable platform for taxiing. The gear legs are made of high-strength steel and are equipped with oleo-pneumatic shock absorbers.

2. Wheel and Brake Assemblies: The MLG and NLG are equipped with wheel and brake assemblies, which provide the necessary braking force during landing and taxiing. The brake assemblies are designed to be highly reliable and are equipped with advanced brake control systems.

3. Linkages and Fittings: The mechanical system includes linkages and fittings that connect the gear legs to the aircraft’s structure. These linkages and fittings are designed to provide a strong and stable connection between the gear and the aircraft.

Electronic System

The electronic system of the 787’s landing gear includes:

1. Landing Gear Control Unit (LGCU): The LGCU is a computer-controlled system that manages the extension and retraction of the landing gear. The LGCU receives input from various sensors and systems, including the flight control computer, and provides output to the hydraulic actuators and valves.

2. Sensors and Switches: The 787’s landing gear system is equipped with a range of sensors and switches that provide feedback to the LGCU. These sensors and switches include gear position sensors, weight-on-wheels sensors, and door position sensors.

3. Electrical Interfaces: The electronic system includes electrical interfaces that connect the LGCU to other systems on the aircraft, including the flight control computer and the hydraulic system.

Operation

The operation of the 787’s landing gear system can be broken down into several phases:

1. Extension: During extension, the LGCU sends a signal to the hydraulic actuators to extend the gear. The hydraulic system provides the necessary pressure and flow to extend the gear, and the gear legs and wheel assemblies move into position.

2. Retraction: During retraction, the LGCU sends a signal to the hydraulic actuators to retract the gear. The hydraulic system provides the necessary pressure and flow to retract the gear, and the gear legs and wheel assemblies move into their stowed position.

3. Taxiing: During taxiing, the NLG is steered using the nose wheel steering system, which is controlled by the flight crew using the tiller.

4. Landing: During landing, the MLG and NLG are designed to absorb the shock of landing and provide a stable platform for the aircraft. The brake assemblies are used to slow the aircraft during landing.

Redundancy and Backup Systems

The 787’s landing gear system includes several redundancy and backup systems to ensure safe and reliable operation. These include:

1. Dual Hydraulic Systems: The 787 has two independent hydraulic systems that can be used to extend and retract the landing gear.

2. Backup Power: The 787 has a backup power system that can be used to power the hydraulic system in the event of a failure.

3. Manual Extension: The 787 has a manual extension system that can be used to extend the landing gear in the event of a failure.

4. Emergency Brake System: The 787 has an emergency brake system that can be used to slow the aircraft in the event of a failure.

In summary, the Boeing 787’s landing gear system is a complex and highly reliable design that incorporates a combination of hydraulics, mechanics, and electronics to ensure safe and efficient operation. The system includes multiple redundancy and backup systems to ensure that the aircraft can be safely operated in a range of scenarios.

Here is YouTube video that further explains the landing gear of Boeing 787

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