Aircraft Nacelle Latch Indication Mechanism for Fan Cowl Verification
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Solution Overview
Problem
Aircraft personnel face challenges in confirming the engagement of latch mechanisms securing fan cowls due to limited visibility, as the latches are located along the underside of the nacelle, requiring them to crouch or bend for inspection.
Innovation Solution
A mechanism featuring a door and arm positioned at eye level, where the arm obstructs the opening when the latch is unlatched, preventing the door from closing, allowing personnel to verify the latch engagement without needing to stoop, and a linkage assembly connecting the arm to a blade that obstructs its retraction when unlatched.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the latch mechanism is located along the underside of the nacelle, then the fan cowls can be secured to one another, but the visibility of the latch during visual inspection is limited
Solution Approach 1:
An indicator arm is introduced as an intermediary component that translates the latch engagement state into a visible position. The arm is mechanically linked to the latch mechanism through a linkage assembly, so when the latch engages or disengages, the arm moves to indicate the state at a visible location on the nacelle exterior, eliminating the need for personnel to inspect the underside directly
Solution Approach 2:
The indicator mechanism transforms the spatial information from the underside location to the exterior surface location. By projecting the latch state information to a different spatial dimension (from hidden underside to visible exterior), personnel can confirm engagement without changing their inspection position or crouching down
2Difficulty of detecting and measuring
If the handle length of the latches is increased to increase visibility underneath a nacelle, then the latches become more visible, but aircraft personnel still need to squat or crouch down to view the underside of the nacelle
Solution Approach 1:
The indicator arm serves as a mediator that transfers the latch position information to a location accessible at eye level. Instead of making the latch itself more visible by extending its handle, the system creates an intermediate indicator that displays the latch state at a convenient viewing height, eliminating the need for personnel to adopt awkward postures
Solution Approach 2:
The system separates the latch mechanism function from the indication function. The latch remains in its original location for securing the cowls, while a distinct indicator arm provides visual feedback. This segmentation allows the indication function to be positioned independently at an ergonomically favorable location without affecting the latch's securing function
3Ease of operation
If a mechanism with arm and door is added to indicate latch engagement at eye level, then visibility and ease of verification are enhanced, but the device complexity increases
Solution Approach 1:
The indicator arm is passively actuated by the latch mechanism itself through the linkage assembly. As the latch engages or disengages, it automatically moves the indicator arm to the corresponding position without requiring additional actuators, power sources, or control systems. This self-service approach provides indication functionality while minimizing added complexity
Solution Approach 2:
The indication function is merged with the existing latch mechanism through mechanical linkage. Rather than creating a separate electronic or independent mechanical indication system, the patent integrates the indicator arm movement with the latch engagement action, so both functions share a common mechanical basis, reducing overall system complexity
Data Source
AI summary
An aircraft nacelle is disclosed and includes a first fan cowl and a second fan cowl. An opening is defined in an exterior surface of the first fan cowl. The aircraft nacelle also includes a blade, a latch mechanism, an arm, and a linkage assembly operably connecting the arm to the blade. The blade is moveable along between a stowed position and a deployed position. The latch mechanism is moveable between a latched position an unlatched position where a portion of the latch mechanism obstructs a path of movement of the blade. The arm is unable to move from an extended position where a portion of the arm extends through the opening in the exterior surface of the aircraft nacelle into a retracted position within an interior volume of the aircraft nacelle when the blade is in the deployed position and the latch mechanism is in the unlatched position.