Stacked Accessory Gearbox Layout for Space-Limited Aircraft Engines

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Solution Overview

Problem

Existing accessory gearboxes in aircraft engines face challenges with limited space for mounting additional accessories, requiring redesigns and additional space, which can lead to further engine revisions.

Innovation Solution

A stacked arrangement of accessories within the gearbox, utilizing a gear assembly that allows multiple accessories to be mounted without increasing the gearbox size, including a planetary gear and sprag gear configuration to enable different operational speeds and simultaneous use of components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If separate mounting pads are used for each accessory on the accessory gearbox, then each accessory can be independently mounted and operated, but the gearbox requires a relatively large amount of space that is often not available at the engine

Engineering Contradiction:

ImproveIndependent mounting and operation of accessoriesVSAvoidSpace required by the accessory gearbox

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The patent applies nesting by stacking the generator accessory on top of the starter accessory, where the generator is positioned within the vertical space above the starter. This nested arrangement allows both accessories to occupy overlapping horizontal footprints while maintaining independent mounting and operation, thereby reducing the overall horizontal space required on the accessory gearbox without compromising operational independence.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If additional accessories are added to the accessory gearbox to upgrade the aircraft, then the aircraft can access additional electrical power, but the lack of physical space makes it difficult or not possible to connect additional accessories

Engineering Contradiction:

ImproveAbility to add additional generators for upgraded electrical powerVSAvoidPhysical space available on the accessory gearbox

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent transitions from a two-dimensional horizontal arrangement of accessories to a three-dimensional stacked configuration. By utilizing the vertical dimension above existing accessories, the system can accommodate additional generators without requiring additional horizontal space on the accessory gearbox, thereby enabling aircraft upgrades while maintaining compact packaging.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If the accessory gearbox size is increased to accommodate additional accessories and separate mounting pads, then more accessories can be mounted, but this requires a redesign of the accessory gearbox and further downstream revisions to the engine and accessories

Engineering Contradiction:

ImproveNumber of accessories that can be mountedVSAvoidRedesign requirements for gearbox and downstream systems

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal mounting interface that can accommodate multiple different accessory types (starters, generators, pumps) through a standardized stacking configuration. The universal adapter plate and mounting pad design allow various accessories to be interconnected in different combinations without requiring custom redesigns, thereby enhancing adaptability while minimizing structural changes to the gearbox and downstream systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20260022669A1Accessory Gearbox with Accessories with a Stacked Configuration

Publication Date: 2026.01.22 THE BOEING CO

AI summary

An assembly that is operatively connected with a connection assembly to a turbine engine of an aircraft. The assembly includes an accessory gearbox with a body configured to be connected to the connection assembly and mounting pads spaced about the body. A first accessory is mounted to the body at a first one of the mounting pads. A second accessory is mounted to the first accessory with the first accessory and the second accessory in a stacked arrangement.