N121-016 TITLE: Wear Indicating Lined Spherical Bearings

TECHNOLOGY AREAS: Air Platform, Materials/Processes

OBJECTIVE: Develop and demonstrate a lined, spherical bearing or rod end bearing assembly with a built in wear limit measurement feature that will provide indication when the minimum allowable liner thickness has been reached.

DESCRIPTION: Lined, spherical bearings are used in a variety of aerospace applications to provide a connection between two structures experiencing rotating and/or misaligning motions. An issue often arises in the ability to measure the wear within a lined bearing especially when the bearing is in a hard to reach/see location or under load. Wear in a lined bearing is inherit and is acceptable to a limit, but beyond that, the bearing becomes more susceptible to failure. The ability to effectively provide indication, once wear in the bearing has reached an allowable limit, can help mitigate the chance of bearing failure and the associated hazards.

A lined spherical stand alone bearing or part of a rod end bearing assembly is desired. The orientation of the bearing within the housing/fixture should not affect the capability of the wear indication (i.e. wear indication should be capable circumferentially). Trial bearing configurations should be comparable to some existing configurations on US Navy or Marine Corp fixed or rotating wing aircraft, where on continuous rotation dynamic components or intermittent rotation applications, such as landing gear, control surface attachments or other control actuators. Bearing and wear indicators must be capable of operating within a rotating environment if applicable. The bearing must also wear in a manner that allows sufficient time from the point of indication that the flight may end prior to reaching an unacceptable liner thickness. The bearing must also wear in a predictable, consistent manner and have a life of at least that currently used in a similar deployed application. The bearing must meet the complete requirements of the associated AS standard. This SBIR would find a solution to prevent bearing failure in multiple aerospace applications by providing indication once the maximum acceptable wear limit has been reached.

PHASE I: Design and develop an innovative approach for a bearing with built in wear indicating features. Identify and define the most effective method to indicate that the minimum liner thickness has been reached and the bearing should thus be replaced. Develop a detailed analysis of the predicted performance of the bearing and indicator in the presence of various environments and contaminates (both fluid and solid). Demonstrate the feasibility of producing the demonstration bearing and outline the success criteria for the demonstration.

PHASE II: Finalize the design and demonstrate practical implementation of a production-scalable prototype bearing. Establish performance parameters through experimentation and prototype fabrication. Evaluate the prototype bearing through demonstration testing.

PHASE III: Transition the approach to the fleet and other candidate platforms.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: A bearing capable of wear limit indication has the potential for transition to the commercial aircraft market for production and maintenance cost reductions and reduced risk of unexpected bearing failure enhancing both safety and reliability.

REFERENCES:
1. ARP 5448/7 Plain Bearing Wear Measurement.

2. ARP 5488/8A Plain Spherical Bearing Radial and Axial Clearance Measurement.

3. SAE ARP5448A Plain Bearing Test Methods.

4. SAE AS81819 Bearings, Plain, Self-Aligning, Self-Lubricating, High Speed Oscillation -65 to +160�F General Specification For.

5. SAE AS81820 Bearings, Plain, Self-Aligning, Self-Lubricating, Low Speed Oscillation.

6. SAE AS81935 Bearings, Plain, Rod End, Self-Aligning, Self-Lubricating, General Specification for.

KEYWORDS: Wear; Indicator; Maintainability; bearing; safety; rod end bearing assembly

** TOPIC AUTHOR (TPOC) **

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