Pivoting Nacelle Inner Structure for Thrust Reverser Maintenance Access
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Solution Overview
Problem
Maintenance operations for thrust reversers with movable cascades are complex and time-consuming due to components being covered by the engine's cowling inner structure, making it difficult to access members located between the engine and the cowling inner structure.
Innovation Solution
The propulsion unit design includes a nacelle cradle with pivotally mounted structural half-shrouds and upstream inner half-structures that form half-sections of the cold flow path, allowing these components to be pivoted outward for maintenance, while maintaining a bifurcation for piping passage and minimizing aerodynamic drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the cowling inner structure is kept fixed and complete, then the structural integrity and aerodynamic performance are maintained, but maintenance operations become complex and time-consuming due to inaccessibility of engine components
Solution Approach 1:
The cowling inner structure is divided into two separate halves that can be independently pivoted outward. This segmentation allows maintenance personnel to access engine components without removing the entire cowling structure, thereby improving ease of repair while maintaining overall structural integrity through the hinge connection to the nacelle cradle.
Solution Approach 2:
The cowling inner structure transitions from a fixed, static configuration to a dynamic one where the two halves can be pivoted outward on hinges. This dynamic capability enables the structure to adapt between its closed aerodynamic configuration during operation and an open configuration during maintenance, resolving the contradiction between maintaining integrity and enabling access.
2Ease of operation
If the cowling inner structure is made removable for maintenance, then component accessibility improves, but the structural integrity and aerodynamic performance deteriorate
Solution Approach 1:
The cowling inner structure is designed as a dynamic system with hinge connections to the nacelle cradle, allowing it to pivot outward for maintenance while remaining structurally attached. This maintains structural integrity and aerodynamic performance during normal operation while enabling component accessibility when needed, without requiring complete removal of the structure.
3Ease of repair
If the thrust reverser flaps and connecting rods are dismounted for maintenance, then complete access to engine components is achieved, but maintenance time and complexity increase significantly
Solution Approach 1:
The cowling inner structure is segmented into two halves that can be independently pivoted outward, creating access pathways to engine components without requiring disassembly of the thrust reverser flaps or connecting rods. This segmentation enables maintenance personnel to access previously inaccessible components while keeping the thrust reverser assembly intact, thereby reducing maintenance time and complexity.
Data Source
AI summary
A turbofan propulsion assembly includes a thrust reverser with movable flaps. The propulsion assembly further includes an engine and a nacelle surrounding the engine, and the nacelle includes a thrust reverser with sliding cowls and thrust reverser flaps, and an inner structure. The portion of the inner structure positioned perpendicular to the thrust reverser flaps includes two halves that can open toward the exterior of the nacelle cowls.