Captured Bolt Assembly With Tethered Cable for FOD Prevention
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Solution Overview
Problem
Bolts pose a significant foreign object debris (FOD) risk during aircraft maintenance, as they can be accidentally dropped and cause damage, necessitating improved bolt capture systems.
Innovation Solution
A bolt system featuring a centrally positioned bolt capture channel with a stop member, such as a swaged cable end, to prevent bolt loss by tethering the bolt to a structure, ensuring it cannot be pulled out of the channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bolt is removed during aircraft maintenance, then the bolt can be accessed and replaced, but the bolt may be accidentally dropped into unreachable areas causing FOD damage
Solution Approach 1:
A cable is introduced as an intermediary element that passes through the bolt capture channel and connects the bolt to the aircraft structure. This cable acts as a physical mediator that prevents the bolt from becoming a free-floating FOD hazard while still allowing it to be removed and replaced during maintenance operations.
Solution Approach 2:
The cable is nested within the bolt capture channel, with the channel providing a protective pathway for the cable. The stop member is then nested onto the cable end, creating a layered protective system where each element is contained within or supported by the previous element.
2Reliability
If a cable is passed through the bolt capture channel, then the bolt is tethered to prevent loss, but the cable may be pulled out of the channel
Solution Approach 1:
The stop member is pre-formed on the cable end before insertion into the bolt capture channel. This preliminary action ensures that when the cable is inserted, the stop member is already positioned to engage with the channel walls, preventing the cable from being pulled out during subsequent maintenance operations.
Solution Approach 2:
The stop member creates a localized expansion or enlargement at the cable end that is specifically designed to match the geometry of the bolt capture channel. This local quality change at the cable end provides a mechanical interference fit that secures the cable in place without affecting the rest of the cable's properties.
3Reliability
If the stop member is larger than the bolt capture channel, then the cable cannot be pulled out, but the stop member cannot fit through the channel
Solution Approach 1:
The cable assembly is segmented into distinct functional zones: the cable body for tension transmission, the stop member for retention, and the cable end for attachment. This segmentation allows each component to be optimized independently - the stop member can be formed to the precise dimensions needed for channel engagement while the rest of the cable maintains its original properties.
Solution Approach 2:
The stop member is formed on the cable end before insertion into the bolt capture channel. This preliminary formation ensures that the stop member's larger dimensions are already in place to prevent cable withdrawal, while the insertion process is simplified because the stop member is already positioned correctly and does not require separate installation steps.
Data Source
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Figure 2
AI summary
A bolt (100) configured for preventing loss of the bolt during removal can include a bolt head (101), a bolt shaft extending from the bolt head (101) in an axial direction, the bolt shaft (103) including threads, and a bolt capture channel (107) defined through the bolt head and the bolt shaft in the axial direction. The bolt capture channel can include a head opening and shaft opening.