Captive Bolt Mounting Plate for Aircraft Engine Nacelle Casing
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Solution Overview
Problem
The existing casing structure between aircraft engines and nacelles hinders maintenance access due to its obstructive nature and relative movement constraints, which complicates maintenance operations and disrupts airflow.
Innovation Solution
A casing structure with a shroud made of sectorized cylindrical frames and radial arms, utilizing captive bolts and nuts with different diameters, and a mounting plate that allows easy removal and reinstallation of shroud sectors for improved accessibility while maintaining aerodynamic continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the casing structure uses a sectorized cylindrical frame with radial arms to provide mechanical junction and protect equipment, then structural strength and equipment protection are improved, but maintenance access to equipment beneath the frame becomes difficult and time-consuming
Solution Approach 1:
The shroud is divided into multiple detachable sectors that can be independently removed. Each sector is connected to the radial arms via fastening means that allow for quick release, enabling maintenance personnel to access equipment beneath the frame without removing the entire casing structure.
Solution Approach 2:
The fastening means between shroud sectors and radial arms are designed to be dynamically adjustable, allowing rapid assembly and disassembly. This dynamic connection system enables the shroud sectors to be easily detached for maintenance and reattached afterward, transforming a static obstructive structure into a dynamically accessible one.
2Stability of the object's composition
If the shroud sectors are securely fastened to radial arms to ensure structural stability, then structural stability is improved, but the time required for removing and replacing shroud sectors during maintenance increases
Solution Approach 1:
The fastening means are pre-configured with alignment features and captive bolts that guide the assembly process. The mounting plates are pre-positioned on the radial arms with alignment pins that automatically orient the shroud sectors correctly during installation, eliminating time-consuming alignment operations while maintaining secure fastening.
Solution Approach 2:
Multiple identical fastening means are distributed around the circumference of the shroud, each being a standardized replica of the others. This standardization allows for rapid replacement of sectors using the same fastening mechanism throughout, reducing maintenance time through repetition of a proven, optimized assembly procedure.
3Object-affected harmful factors
If the casing structure uses a solid frame design to provide fireproofing protection and structural support, then protection and support functions are improved, but the aerodynamic flow passage continuity is disrupted
Solution Approach 1:
The shroud is segmented into multiple sectors with gaps between them that allow aerodynamic flow passage continuity. These gaps are positioned strategically to minimize disruption to the bypass stream while the sectors themselves provide the necessary fireproofing protection and structural support where needed.
Solution Approach 2:
The shroud sectors provide fireproofing protection and structural support only in the specific locations where they are mounted, rather than forming a complete continuous barrier. This localized approach allows the bypass air to flow continuously through the gaps between sectors while still providing protection and support at critical points.
Data Source
AI summary
An aircraft casing structure including a shroud surrounding the engine and made up of a plurality of sectors; a plurality of radial arms, each mounted between two adjacent shroud sectors and each having a base; and a plurality of fasteners for fastening the shroud sectors on the bases of the radial arms; the fasteners including a plurality of plates each mounted flush in a respective groove of corresponding shape in a shroud sector, and a set of headed bolts held captive in the plate by a difference of diameter between their shanks and their threads, a set of captive nuts being fastened to the bases to provide a secure connection between the shroud sectors and the radial arms by each nut receiving the thread of a respective captive bolt of the set of headed bolts.