Aircraft Landing Gear Brake Cross-Connection Testing Without Wheel Spin

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Solution Overview

Problem

Conventional methods for testing aircraft landing gear for cross-connections between braking systems require raising the landing gear, use of drills to spin wheels, and involve multiple operators, making them inefficient and cumbersome.

Innovation Solution

A method using tachometers to generate test signals without rotating the wheels, allowing the braking control and monitoring system to issue and monitor braking commands, thereby testing for cross-connections between braking systems with reduced operational requirements, including the use of a floating connection to enable tachometer rotor rotation without wheel rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conventional method of spinning wheels with drills is used to test for cross-connections, then the braking system can be tested, but the landing gear must be raised from the ground and multiple operators are required

Engineering Contradiction:

Improvecross-connection detection capabilityVSAvoidoperational complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical drill-based wheel spinning system with an electrical test signal injection system. The tachometer generates electrical test signals that are processed by the braking control system, eliminating the need for mechanical wheel rotation devices like drills and the complex ground support equipment required.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The braking control system uses its own tachometer and control electronics to generate test signals and process responses, making the system self-testing rather than requiring external drill equipment and multiple operators. The system tests itself using existing onboard components.

Inventive Principle:

Principle #25Self-service

2Reliability

If the conventional method using drills to spin wheels is used, then cross-connection testing is possible, but the process requires three operators and is time-consuming

Engineering Contradiction:

Improvecross-connection detection capabilityVSAvoidtesting efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The test signal is generated and injected into the system before any physical wheel rotation is required. The tachometer and braking control system are pre-configured to generate and process test signals, allowing the testing to begin immediately without the preliminary setup of drill equipment and multiple operators.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If a floating connection is used to enable tachometer rotor rotation without wheel rotation, then test signal generation is simplified, but the mechanical coupling is modified

Engineering Contradiction:

Improvetest signal generation capabilityVSAvoidtachometer mechanical structure

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent segments the tachometer rotor from the wheel by introducing a floating connection. This allows the rotor to be independently rotated to generate test signals without rotating the entire wheel assembly, separating the signal generation function from the wheel rotation function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The floating connection changes the mechanical parameter of coupling between the tachometer rotor and wheel, allowing relative motion and independent rotation of the rotor. This parameter change enables the rotor to be rotated through a limited range to generate test signals without requiring full wheel rotation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3940365B1Cross-connection test for aircraft landing gear

Publication Date: 2024.10.30 AIRBUS OPERATIONS LTD

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AI summary

A method of testing an aircraft landing gear. The landing gear comprises first and second wheels; a first braking system comprising a first tachometer mounted to the first wheel and configured to generate a first tachometer signal indicating rotation of the first wheel, and a first brake configured to brake the first wheel; a second braking system comprising a second tachometer mounted to the second wheel and configured to generate a second tachometer signal indicating rotation of the second wheel, and a second brake configured to brake the second wheel; first and second tachometer output lines; a first braking command line associated with the first tachometer output line; and a second braking command line associated with the second tachometer output line. The method comprises: a) generating a test signal with the first tachometer, wherein the first wheel is not rotating during the generation of the test signal; b) receiving the test signal via one of the tachometer output lines; c) issuing a braking command in response to the receipt of the test signal, wherein the braking command is issued via the braking command line which is associated with the one of the tachometer output lines; and d) monitoring a response of the first or second braking system to the braking command to test for a cross-connection between the first and second braking systems.