Propeller Restraint Boot Tethering for Turboprop Aircraft
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Solution Overview
Problem
Conventional propeller restraints for turboprop aircraft face issues with maintaining secure and reliable installation tension over time, as tethers such as bungee-type cords may stretch and length-adjustable straps may become worn.
Innovation Solution
The proposed propeller restraint kit includes open-ended propeller restraint boots with grommeted drain holes, tether straps of predetermined length or with length adjusters, and a cowling attachment assembly featuring a quick disconnect pin assembly and pin receiver for secure attachment to the aircraft cowling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bungee-type cords are used as tethers in propeller restraints, then ease of operation and initial tensioning is improved, but reliability deteriorates over time due to stretching
Solution Approach 1:
The patent transitions from using elastic bungee cords to non-extensible tether straps with fixed or adjustable length, changing the physical parameter of extensibility to eliminate stretching while maintaining ease of installation through the quick disconnect mechanism
Solution Approach 2:
The patent employs replaceable tether straps and boots that can be easily swapped out when worn, treating these components as consumable items that ensure reliable tensioning without the need for complex adjustment mechanisms
2Adaptability or versatility
If length-adjustable straps are used in propeller restraints, then adaptability is improved, but reliability deteriorates due to wear of adjustment mechanisms
Solution Approach 1:
The patent changes the state of the tether from adjustable to fixed-length non-extensible straps, eliminating the wear-prone adjustment mechanisms while maintaining sufficient adaptability through the quick disconnect system that allows easy replacement of the entire strap assembly
3Device complexity
If conventional tether systems are used, then simplicity of device is maintained, but reliability deteriorates due to inability to maintain consistent tension
Solution Approach 1:
The patent divides the restraint system into modular components (propeller boots, tether straps, quick disconnect assemblies) that can be independently replaced, maintaining overall system simplicity while ensuring reliable tension through replaceable parts rather than complex adjustment mechanisms
Solution Approach 2:
The quick disconnect assembly acts as an intermediary mechanism that simplifies the connection between tether straps and mounting points, enabling reliable and consistent tensioning while maintaining ease of operation through standardized coupling and decoupling actions
Data Source
AI summary
Propeller restraint kits for turboprop aircraft are provided which include at least one, and preferably a pair, of propeller restraint systems. Each propeller restraint system will preferably include an open-ended propeller restraint boot that may be formed of a flexible and durable fabric material which is sized and configured for placement over the tip of a propeller blade. A cowling attachment assembly is provided in the kit and is adapted to being attached to an aircraft cowling skin. A propeller boot tether strap of predetermined length interconnects the propeller restraint boot and the cowling attachment assembly. The cowling attachment assembly includes (i) a quick disconnect (QD) pin assembly connected to a terminal end of the propeller boot tether strap, and (ii) a pin receiver adapted to being positionally attached to an interior portion of the aircraft cowling skin.