Aircraft Autothrottle Breakaway Link for Jam-Tolerant Manual Control

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Solution Overview

Problem

Existing aircraft throttle systems, particularly those with two independent levers for controlling turbine engines or turboprop systems, face challenges in maintaining functionality during mechanical jams or failures, which can disrupt the operation of both propeller pitch and turbine speed control.

Innovation Solution

A single lever throttle system with a mechanical connection using a breakable link, such as rivets, that shears upon excessive force, allowing manual operation when the servo or mechanical connection jams, ensuring independent RVDTs continue to function and transmit signals to the FADEC controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a mechanical connection is made between the servo output mechanism and the throttle lever, then the autothrottle system can control the throttle automatically, but the system becomes vulnerable to mechanical jams that can disrupt operation

Engineering Contradiction:

Improveautothrottle controlVSAvoidsystem operation during mechanical failure

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The mechanical connection is segmented into a breakable link (such as a frangible rivet or shear pin) that can disconnect the servo output mechanism from the throttle lever when excessive force is applied, allowing the system to fail safely and maintain manual operation capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The breakable link is designed in advance to fail at a predetermined force threshold, cushioning the system against the harmful effects of mechanical jams by preventing transmission of excessive forces that could damage other components or completely disable the throttle system

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of operation

If the servo output mechanism is mechanically connected to the throttle lever, then automatic throttle control is achieved, but manual operation becomes difficult when the mechanical connection jams

Engineering Contradiction:

Improvemanual throttle controlVSAvoidthrottle operation during mechanical jam

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The potential harm of a mechanical jam is converted into a beneficial failure mode where the breakable link shears off, allowing the throttle lever to be manually operated independently of the jammed servo mechanism, thus transforming a system failure into a safe operational state

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If a breakable link is included in the mechanical connection, then manual operation is possible during failure, but the mechanical connection becomes less robust

Engineering Contradiction:

Improvemanual operation capabilityVSAvoidmechanical connection strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The mechanical connection has non-uniform strength distribution, with the breakable link having locally reduced strength compared to other components, allowing it to fail first and protect the rest of the system while maintaining overall connection integrity during normal operation

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12583603B2Autothrottle system for aircraft

Publication Date: 2026.03.24 TEXTRON INNOVATIONS INC

AI summary

Disclosed is an automatic throttle arrangement utilizing a servo which receives commands from a controller on an aircraft and responsively rotates a mechanical device that is linked by a cable arrangement with the aircraft's throttle lever enabling automated throttle control. The mechanical device can be fixed to the throttle lever assembly using rivets designed to fail in case the servo/cable arrangement jams. This leaves the lever able to continue manual function.