Flap Actuator Redundant Load Path Design
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Solution Overview
Problem
Existing hydraulic systems for aircraft flap actuators are complex, costly, and difficult to diagnose and repair, with multiple hydraulic lines required for redundancy, leading to weight and maintenance challenges.
Innovation Solution
A flap actuator with a redundant load path design, featuring a shaft with a no-back assembly, ball nut, and gear assembly, including a one-way roller clutch and gimbals, which allows for simple installation and service, and maintains flap position under compressive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic system with multiple hydraulic lines is used to ensure redundancy, then the reliability of the flap actuator is improved, but the device complexity and weight increase
Solution Approach 1:
The hydraulic system is segmented into two independent single-line systems (system A and system B), each capable of independently actuating the flap. This eliminates the need for multiple hydraulic lines per actuator while maintaining redundancy through system-level duplication rather than component-level multiplication.
Solution Approach 2:
Each hydraulic system (A and B) is designed to be universal and capable of independently performing the complete flap actuation function. Either system alone can provide full redundancy, allowing the system to maintain reliability while reducing overall complexity by eliminating redundant lines at each actuator.
2Reliability
If a conventional hydraulic system with centralized pumps is used, then the flap actuator maintains reliable operation, but the ease of repair deteriorates
Solution Approach 1:
The centralized hydraulic system is segmented into two independent single-line systems. Each system can be independently diagnosed and repaired without affecting the other, significantly improving ease of repair while maintaining reliable operation through the independence of the segmented systems.
3Reliability
If multiple hydraulic lines are run to each flap actuator for redundancy, then the reliability is improved, but the weight increases
Solution Approach 1:
The hydraulic architecture is segmented into two independent single-line systems rather than using multiple lines per actuator. This segmentation reduces the total weight of hydraulic lines while maintaining redundancy through system-level independence.
Solution Approach 2:
Each single-line hydraulic system is designed to be universal and capable of independently actuating the flap. This multi-functionality allows either system to provide full redundancy, eliminating the need for multiple lines per actuator and thereby reducing overall system weight.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a lightweight, easy-to-service flap actuator that ensures reliable operation and redundant load sharing, reducing maintenance complexity and costs while maintaining flap position effectively.
Implementation Method 1
The shaft includes a hollow ball screw extending along the longitudinal axis and an inner bar extending through the ball screw
Implementation Method 2
A one-way roller clutch is operatively connectable to the ball nut. The roller clutch engages the housing and prevents rotation of the ball nut in a first direction in response to a compressive force on the ball screw by the flap
Implementation Method 3
A no-back assembly is operatively connectable to the shaft. The no-back assembly prevents movement of the shaft toward the retracted position in response to a compressive force generated by the flap
Implementation Method 4
A no-back assembly includes a housing for supporting the shaft and a first gimbal for interconnecting the housing to the wing. A second gimbal also interconnects the housing to the wing
Data Source
AI summary
A flap actuator is provided for controlling movement of a flap on a wing of an aircraft. The flap actuator includes a housing having a leading end and a trailing end. A ball nut is rotatably supported in the housing. A motor has a rotatable drive shaft that is rotatable in first and second opposite directions. A gear assembly translates rotation of the drive shaft to the ball nut. A ball screw extends along a longitudinal axis and has a terminal end operatively connectable to the flap. The ball screw is movable between a first retracted in response to rotation of the ball nut in a first direction and a second extended position in response to rotation of the ball nut in a second direction. A one-way roller clutch is operatively connectable to the ball nut. The roller clutch engages the housing and prevents rotation of the ball nut in a first direction in response to a compressive force on the ball screw by the flap. First and second concentric gimbals are positioned about the longitudinal axis adjacent the housing. The gimbals interconnect the housing to the wing.