Propeller Blade Taper Bore Reaming With Integrated Inspection
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Solution Overview
Problem
Current aircraft propeller maintenance processes are costly and inefficient, with existing methods failing to effectively prevent structural issues like cracking and fatigue, leading to potential catastrophic failures, and requiring extensive testing and rework that increases maintenance costs and parts inventory.
Innovation Solution
A system and method for precision taper bore reaming using a custom horizontal mill, blade holding fixture assembly, and specialized tooling, including air gauges and fluorescent penetrant inspection, to refurbish aircraft propeller blades, ensuring compliance with industry standards and reducing maintenance costs through improved accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If proactive testing and rework are performed on propellers to detect structural issues, then reliability is improved, but maintenance costs and parts inventory increase
Solution Approach 1:
The patent applies preliminary action by performing testing and rework procedures on propellers before they fail in service. The system identifies structural issues through non-destructive inspection methods and performs corrective rework while the propeller is still in the maintenance facility, preventing catastrophic failures before they occur in operational conditions.
Solution Approach 2:
The patent implements self-service by developing an integrated maintenance system that combines testing, inspection, and rework capabilities within the same facility. This allows the maintenance operation to handle its own propeller refurbishment needs without requiring extensive spare parts inventory, as propellers can be tested and reworked on-site rather than replaced with spare units.
2Reliability
If extensive testing and rework procedures are implemented, then propeller reliability is improved, but maintenance time and costs increase
Solution Approach 1:
The patent merges multiple maintenance functions into a single integrated system. Testing equipment, non-destructive inspection facilities, and rework machinery are combined in one maintenance facility, allowing propellers to undergo complete refurbishment cycles without being moved between different shops or facilities, thereby reducing overall maintenance time despite the comprehensive nature of the procedures.
Solution Approach 2:
The patent maintains continuity of useful action by implementing a streamlined workflow where testing, inspection, and rework procedures are performed in sequence without interruption. The integrated facility allows propellers to move continuously through the maintenance process, eliminating downtime associated with transporting parts between different maintenance locations or waiting for external services.
3Manufacturing precision
If traditional testing and rework methods are used, then propeller maintenance is performed, but accuracy and precision are insufficient
Solution Approach 1:
The patent replaces traditional mechanical measurement and inspection methods with more advanced technologies. Non-destructive inspection methods such as eddy current testing, ultrasonic testing, and other non-mechanical detection systems are employed to identify structural issues with higher precision than conventional mechanical measurement tools, while automated rework equipment provides more accurate material removal and restoration than manual processes.
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 system enables efficient and accurate refurbishment of aircraft propeller blades, reducing the risk of structural failures by precision reaming and shot peening, while minimizing maintenance costs and inventory needs, by allowing for quicker and more precise inspection and rework processes.
Implementation Method 1
testing the reamed surfaces with an air gauge
Implementation Method 2
a fluorescent penetrant emersion fixture
Implementation Method 3
reaming shot peened surfaces
Data Source
AI summary
This invention relates to both process and tooling for machining exemplary Hamilton Sundstrand 7111 and 7121 aircraft propeller blade taper bores, or equivalent to comply with government and or industry standards or specifications for such refurbishment. The tooling and process invented are an Improvement over previous and current taper bore machining methods in improved repeatability and cost effectiveness, as this machining method can quickly and repeatedly machine propeller blades to meet fit, form, and function requirements. The process makes use of a specially constructed horizontal mill, specially constructed blade-holding fixture, specially constructed probing system, specially constructed reamers, and specially constructed air gauges. A blade holding fixture assembly including a base plate, a blade holding fixture and a blade alignment fixture hold an aircraft propeller blade in a horizontal milling machine for refurbishment of the taper bores. Refurbishment includes reaming shot peened surfaces, testing the reamed surfaces with an air gauge and a fluorescent penetrant emersion fixture.