Indexed Latch Hook Adjustment for Compact Fan Cowl Closure
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Solution Overview
Problem
Existing latch assemblies for aircraft fan cowls struggle to accommodate various nacelle configurations and geometrical changes, leading to issues such as aerodynamic drag and weight, while existing adjustable latch mechanisms face challenges in limited spaces.
Innovation Solution
A latch hook adjustment assembly with a bearing block and nut configuration that allows for adjustable positioning of the latch hook, utilizing indexing features to prevent rotation during use and enable precise adjustment, thus accommodating different nacelle geometries without increasing height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a larger nacelle/fan cowl is used to accommodate build tolerance and geometrical changes, then the latch assembly can be made adjustable, but aerodynamic drag and weight increase
Solution Approach 1:
The latch hook is made adjustable through a bearing block with indexing features that can be repositioned along the shaft to different axial locations. This dynamic adjustability allows the latch assembly to adapt to build tolerance and geometrical changes without requiring a larger fan cowl structure.
Solution Approach 2:
The axial position of the latch hook can be changed by rotating the bearing block to different indexed positions, allowing the latch assembly to accommodate variations in nacelle geometry while maintaining a compact design that does not increase weight.
2Adaptability or versatility
If a larger nacelle/fan cowl is used to accommodate build tolerance and geometrical changes, then the latch assembly can be made adjustable, but aerodynamic drag increases
Solution Approach 1:
The adjustable latch hook allows precise positioning to match the actual geometry of the nacelle, ensuring a compact and aerodynamic closure without requiring excessive clearance or a larger overall structure that would increase drag.
Solution Approach 2:
By changing the axial position of the latch hook through indexing, the assembly can achieve optimal positioning for aerodynamic efficiency while accommodating build tolerance, avoiding the need for a larger drag-inducing structure.
3Weight of moving object
If a smaller/thinner fan cowl configuration is used, then aerodynamic drag and weight are reduced, but the latch assembly becomes difficult to accommodate in limited spaces
Solution Approach 1:
The bearing block with indexing features is nested within the latch hook assembly, allowing the adjustment mechanism to be compact and integrated within the limited space of a thin fan cowl configuration while maintaining full adjustability functionality.
Solution Approach 2:
The compact indexing mechanism allows the latch hook to be adjusted to different positions within a limited axial space, enabling the fan cowl to be made thinner while still providing the necessary adjustability for build tolerance accommodation.
4Object-affected harmful factors
If a smaller/thinner fan cowl configuration is used, then aerodynamic drag is reduced, but the latch assembly becomes difficult to accommodate in limited spaces
Solution Approach 1:
The indexing adjustment mechanism is nested within the compact latch hook assembly, enabling the fan cowl to be designed with reduced thickness for aerodynamic efficiency while the integrated bearing block provides the necessary adjustment capability within the constrained space.
Solution Approach 2:
The axial position parameter of the latch hook can be varied through indexing within a compact range, allowing the fan cowl to be optimized for aerodynamic drag reduction while the adjustability mechanism fits within the limited spatial envelope.
Data Source
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AI summary
A latch mechanism (34) is provided that includes a latch housing (36), latch keeper (40), and a latch hook adjustment assembly (38). The latch hook adjustment assembly (38) includes a latch frame (44), latch handle (46), hook member (48), bearing block (50), a nut (52), and a spring member (54). The latch frame (44) has a front wall (56), an interior wall (66), and a forward cavity (70). The hook member (48) has a partially threaded shaft (84). The bearing block (50) has a flange (92), indexing features (96), and a bore. The flange (92) has opposing first and second side surfaces. The indexing features (96) project outwardly from the second side surface (102) and are disposed adjacent the bore. The nut (52) has first and second axial end surfaces (104, 106), a threaded nut bore (110), and index cavities (114) disposed in the first axial end surface (104) adjacent the nut bore (110). The bearing block (50), nut (52), and spring member (54) are disposed in the forward cavity (70). The latch hook adjustment assembly (38) is disposable in engaged and disengaged configurations.