Remote Accessory Gearbox Layout for Easier Aircraft Maintenance
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Solution Overview
Problem
Conventional aircraft gas turbine engines face challenges in maintaining and servicing accessory gearboxes due to their proximity to the engine, which complicates maintenance and increases costs.
Innovation Solution
A remote mounted accessory gearbox system is implemented, featuring a tower shaft with flex joints to accommodate engine movement, a reduction gearbox for speed adjustment, and a flexible interface for controlling engine operations, allowing the gearbox to be positioned lower in the aircraft for easier access and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the accessory gearbox is mounted close to the engine, then the power transmission is efficient and compact, but the maintenance and servicing becomes difficult and costly
Solution Approach 1:
The power transmission system is segmented into two independent parts: the engine remains in its original position, while the accessory gearbox is separated and mounted remotely in the airframe. This segmentation allows the gearbox to be accessed easily for maintenance while still being powered by the engine through the tower shaft.
Solution Approach 2:
A tower shaft acts as an intermediary element to transmit power from the engine to the remotely mounted accessory gearbox. This intermediary component enables the separation of the gearbox from the engine, allowing independent positioning for maintenance accessibility while maintaining power transmission functionality.
2Ease of operation
If the accessory gearbox is mounted remotely in the airframe, then maintenance accessibility is improved, but the tower shaft must accommodate engine movement and positioning variations
Solution Approach 1:
The tower shaft is designed with flexible joints that allow it to accommodate dynamic movements of the engine relative to the airframe. This dynamic capability enables the remote mounting of the gearbox while maintaining power transmission despite engine positioning variations during operation.
Solution Approach 2:
The tower shaft incorporates flex joints that change its effective rigidity parameter to accommodate engine movement. The joint can flex and adjust its position to absorb movements in the engine, maintaining continuous power transmission to the remotely mounted gearbox.
3Adaptability or versatility
If the tower shaft includes flex joints to accommodate engine movement, then the remote mounting is feasible, but the power transmission efficiency may be reduced
Solution Approach 1:
The flex joint acts as an intermediary element in the tower shaft that transmits power while accommodating engine movement. Despite the flexibility, the joint is designed to maintain adequate power transmission efficiency by minimizing energy loss while allowing the necessary movement accommodation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates easier maintenance and reduces maintenance costs by providing accessible components and improved engine control through a remote interface, enhancing operational efficiency and accessibility.
Implementation Method 1
the tower shaft comprises a flex joint adjacent the engine, the flex joint configured to accommodate movement of the engine in relation to the accessory gearbox
Implementation Method 2
a reduction gearbox arranged between a main shaft of the engine and the tower shaft, the reduction gearbox configured to rotate the tower shaft at a different rotation speed than the main shaft
Implementation Method 3
a first set of gears arranged between the tower shaft and the first shaft, the first set of gears configured to rotate the first shaft at a different rotational speed from the tower shaft
Implementation Method 4
a second set of gears arranged between the tower shaft and the second shaft, the second set of gears configured to rotate the second shaft at a different rotational speed from the tower shaft
Data Source
AI summary
An apparatus includes an engine and an accessory gearbox. The engine is positioned on a top side of an aircraft. The accessory gearbox is mounted with an airframe of the aircraft remote from the engine, wherein the accessory gearbox is drivingly connected to the engine.