BAA-RQKPD-2015-0001-Call4-Atch1.pdf

BAA-RQKPD-2015-0001

Call # 0004

Attachment 1 - SOO

Composite Airframe Life Extension (CALE) Demonstration 1 Demonstration of Extended Durability Life

STATEMENT OF OBJECTIVES

14 Aug 2017

Background

Use of structure manufactured from advanced composite materials is now commonplace in USAF aircraft. Most of the USAF aircraft operating today, and for the foreseeable future, contain some advanced composite structure. In the case of more recently acquired aircraft, advanced composite structure makes up a significant portion of the airframe, and is used in large-scale, primary structure such as wing and horizontal tail skins, ribs, and spars, and fuselage skins, frames, and longerons.

The USAF has an established history of operating aircraft well beyond their design service lifetimes, and has developed proven, sound engineering methods and practices for doing so.

These practices, often implemented through formal Service Life Extension Programs (SLEP) have been developed, refined, and validated for metal aircraft structure, primarily aluminum.

Conversely, the Air Force has no significant experience in assessing service history of advanced composite structure, determining and selecting new service life objectives, and verifying that the aircraft structure will remain airworthy throughout the extended service life.

The Air Force Research Laboratory intends to develop an approach to: (1) Assess existing design data related to establishing the initial durability life of in-service advanced composite structure for use in establishing additional durability life (2) Identify and collect material and structural performance data necessary to verify additional durability life is achievable (3) Identify and develop improved methods to predict the durability of advanced composite airframe structure and (4) demonstrate a process for validating the structure remains airworthy up to the new durability life limit.

Research Program Description:

This research program will assume that the USAF desires to achieve a Service Life Extension for an in-service USAF aircraft containing primary structure manufactured using advanced composite materials. The specific aircraft is to be determined and proposed by the contractor.

This notional Service Life Extension is to be for 50% additional durability life with respect to the original full-scale durability test demonstrated life at B-Basis equivalent reliability. It is further desired that this durability extension be achieved without replacement of the composite structure and without major modifications to reinforce or repair the composite structure. To simplify the problem, it will be assumed that the usage spectrum is the same as was used for the original full scale durability test. This objective 50% increase will be referred to as the durability life extension goal.

Note that AFRL/RQVS is not intending to validate a specific Service Life Extension for a specific aircraft structure, AFRL/RQVS intends to validate an approach that is applicable to a wide array of composite and/or composite components of hybrid composite/metallic airframe structures, for use in future to be determined SLEP effort.

To complete this validation with acceptable engineering rigor, AFRL/RQVS envisions 3 major technical tasks, in addition to activity required for project management and reporting of results.

Task 1 is related to the collection and analysis of engineering design data related to demonstrating the original durability life of the baseline composite structure, assessing the sufficiency of this heritage data for predicting the durability of the baseline advanced composite structure, and determining what, if any, additional engineering data is needed to achieve the durability life extension goal. Such data may not exist and in that case will require development. Task 2 is the technical effort required to develop, through test, analysis, or such other methods as may be proposed, the missing data required to achieve the durability life extension goal. Task 3 is the demonstration that the durability life extension goal is achieved at the B-basis equivalent reliability. Other tasks may be required to complete this effort, and other technical activities may be required in the performance of each task as described by AFRL/RQVS. The offeror is free to propose such, within the scope and budget of the program.

To provide realistic structural design problems, performance requirements, and quantifiable program objectives and measures of success, this program envisions the use of a baseline structural demonstration component. Offerors are strongly cautioned to propose only baseline structures for which they have access to, or can readily obtain, significant design heritage data.

Offerors are strongly encouraged to make maximum use of such data. (Design heritage data includes, but is not limited to, materials property databases, specific structural requirements and design criteria, design development analysis, design development test results, and airworthiness certification test results.) Offerors should note that AFRL/RQVS does not have ownership of, nor does it control access to, such design heritage data for existing USAF aircraft structure, and therefore cannot provide such as government furnished property (GFP) or government furnished information (GFI) to any potential offeror.

The intent of this CALE project is to develop, demonstrate, and transition methods of predicting and verifying extended durability life limits to both the US government and to industry. For this reason, all prior CALE projects have been conducted to produce data in accordance with Scientific and Technical Information Distribution Statement C: Distribution authorized to U.S.

Government agencies and their contractors. To the greatest extent possible, AFRL/RQVS desires to maintain this intent, however, AFRL/RQVS also recognizes that critical design details of the baseline structure may require the more stringent Distribution D. AFRL/RQVS also recognizes that some aspects of the technical baseline of the baseline demonstration component may include proprietary information, requiring proprietary restrictions. This is an acceptable condition with respect to the baseline demonstration component only. In this R&D project, AFRL is not interested in proposals to apply company proprietary technologies to assess, predict, and verify the durability life extension, or validate the durability life extension meets the objective, and as such should not be proposed.

The testing facilities of the Air Force Structures Test Laboratory at the Air Force Research Laboratory (AFRL) Wright-Patterson AFB may be made available for use in the performance of this effort. Potential contractors who may be interested in using AFRL test facilities are advised that the cost of performing testing and test related tasks in AFRL will be paid within the overall project budget and cannot be considered additional resources. Therefore, the estimated cost of testing within AFRL must be provided as a discrete item in the contract cost proposal. Any testing using proposed government facilities must be detailed enough that the Government will be able to develop an internal testing budget. Contractors wishing to use the AFRL testing facility will need to provide their test plan or test requirements document to Kenneth Leger, 937-656-8833, kenneth.leger@us.af.mil NLT 14 September 2017 in order to receive a timely cost estimate.

Statement of Objectives:

The overall objective of this program is to validate an approach for verifying that a prior, established service life capability for an existing composite airframe may be increased, at low risk, during the service life of the aircraft fleet, such as would be required for a Service Life Extension Program. (SLEP) Low risk, in this case, is considered to be equivalent reliability with metallic structure subject to the same SLEP. To validate this reliability, verification testing will be performed to demonstrate 90% reliability at the increased service life capability with 95% confidence (B-Basis equivalent reliability). To accomplish such testing in an economic manner, load enhancement factors are to be developed and applied within the program, using data relative to the composite materials and structural design configuration and features of the specific airframe structure being used to demonstrate this durability life extension.

Task 1 – Select baseline demonstration structure, assess durability life extension goals, and identify the design analysis data needs: The contractor shall select a baseline demonstration component. The baseline demonstration component shall be at least a major component from an airframe currently in service within the USAF fleet as part of an aircraft having an MDS designation. In this usage, major component can be interpreted to be a discrete and relatively complete section of the aircraft structure, such as a wing, a horizontal or vertical stabilizer, or a fuselage in which composites carry primary loads. Other components are feasible and may be proposed. The key aspect here is that the structural component should be an assembly of several subcomponents. The baseline demonstration component may be composed entirely of advanced composite structure, or may be a mixture of advanced composite and metallic subcomponents. There are no restrictions on the methods used to assemble the subcomponents into the component. The contractor shall review existing “heritage data” used to complete the baseline demonstration component design, development, and airworthiness certification testing and perform an initial durability life extension analysis for the advanced composite structure of the baseline demonstration component. In performing this assessment, the contractor may include the effects of minor modifications to the structure to reduce the risk of achieving the durability life extension goal. In this usage, “minor modification” is meant to imply small, localized reinforcements such as fastener bushings to fill oversize holes, reinforcing plates and straps, and similar, limited features. Redesigning individual composite parts of the structure, adding large reinforcing structure similar to a major repair, or material substitution for improved properties does not meet the objectives of the program.

The contractor shall recommend data, tests and test results, and analysis results that are sufficient to verify the durability life extension goal of 50% increase with respect to the original full-scale durability test demonstrated life at B-Basis equivalent reliability. The contractor shall identify data gaps requiring additional testing, or other forms of risk reduction, such as analysis, required to verify the advanced composite structure within the baseline demonstration component will achieve the durability life extension goal.

The contractor shall prepare a Durability Life Extension Data Development Plan sufficient to provide the missing property data, analysis results, or other information required to determine if achieving the durability life extension goal is viable. This plan is envisioned as combination of test results and incremental analysis similar to a building-block risk reduction effort, but would concentrate on providing the data necessary to establish the increased durability of the composite components of the airframe. Other approaches may be feasible, and are not excluded from consideration. The contractor shall present the durability life extension data development plan to AFRL/RQVS for approval.

In the performance of this task, the contractor is strongly advised to concentrate on data, methods, and information necessary to determine the feasibility of achieving the extended durability life goal for the advanced composite structural elements. The influence of the metallic structure on the performance of the composite structure, such as load transfer at joints in the structure, may be of significance and should be considered in this program.

Whether the metallic structure can meet either goal, specifically, is not of interest to the program and should not be the basis for not achieving the durability life extension goal.

Task 2 – Develop and obtain data and perform analysis required to determine durability life extension and develop load enhancement factors: Upon approval from AFRL/RQVS to proceed, the contractor shall execute the Durability Life Extension Data Development Plan. The contractor shall review the results of the Durability Life Extension Data Development Plan and may propose minor modifications, subject to the same conditions as in Task 1 above, to reduce the risk of achieving the durability life extension goal. Offerors are reminded that if such modifications are proposed, they must be designed, developed, and shown to meet airworthiness requirements within the budget of the program. Upon completion of the Durability Life Extension Data Development Plan, the contractor shall determine the feasibility of achieving the life extension goal (with and without proposed modifications) during the testing described in task 3. The contractor shall compute load enhancement factors to be applied to verify the durability demonstrated through testing is equivalent to a B-Basis reliability as a function of various durability test durations. The contractor shall prepare the Validation of Durability Life Extension Test Plan. In preparing this plan, the contractor shall identify, and, as required, design the specific advanced composite test articles to be used for the validation testing. In the development of this Validation of Durability Life Extension Test Plan, the contractor is encouraged to consider the effects of joints between composite structures to be tested and metal structures not to be tested, and to look for innovative ways of accurately capturing load transfer stresses and strains in the composite structure due to such joints as part of the test plan. The contractor is encouraged to consider the broad goals of this program, and to develop an approach that is generally applicable to a wide range of aircraft structure, for demonstration within the resources of the program. Test programs may include, but are not limited to:

Testing additional replicates of the structural validation test articles, but subjected to different load enhancement factors. This may include testing to compare the accuracy of multiple approaches to computing load enhancement factors.

Testing additional replicates of the structural validation test articles to additional (different) load spectrums to represent possible new mission uses for the baseline aircraft.

Testing of newly manufactured structural validation test articles.

Testing structural validation test articles obtained by removing structure from in-service aircraft.

Testing to include metallic structures, as appropriate, to accurately capture boundary condition constraints and/or load transfer and stresses and strains at composite to metallic joints.

Post-test structural tear down, where appropriate, and examination of test articles to detect and assess damage/degradation not detectable or measurable during the test itself.

The contractor is free to propose the above, plus any additional test conditions selected to improve the quality of the validation demonstration. The Validation of Durability Life Extension Test Plan shall document the testing required, to include test fixture design, load introduction, test load spectrum, test data collection requirements, test instrumentation locations such as strain and deflection gauges, test article inspection requirements and other details necessary to fully describe the intended durability validation testing. The contractor shall present the Validation of Durability Life Extension Test Plan to AFRL/RQVS for approval.

Task 3 – Validation of durability life extension of advanced composite structure using load enhancement factors: Upon approval from AFRL/RQVS, the contractor shall conduct testing (with or without proposed modifications also subject to approval from AFRL/RQVS) sufficient to validate the required durability life extensions for the advanced composite structures within the baseline demonstration component. The test program shall employ the load enhancement factor and test duration agreed upon between the contractor and AFRL/RQVS that is expected to demonstrate an equivalent B-Basis reliability. The contractor shall collect test data required to assess the success of durability life extension testing and to validate analysis predictions.

Task 4 – Document and report results to relevant US Government Agencies and US Industry:

The contractor shall prepare quarterly technical and final technical reports documenting technical activity conducted during this program, to include assessing results, documentation of lessons learned, and observations related to capabilities and remaining technical challenges.

The contractor shall prepare and present a final review of the research results to US Government and US Industry as directed by AFRL. The contractor shall plan for reporting technical results, lessons learned, and observations related to capabilities and remaining technical challenges to US industry and government at least twice via technical conference or government and industry workshop, and shall consult with AFRL/RQVS regarding opportunities and venues to do so.

Security - Operations Security (OPSEC) must be an integral part of our daily activities. As we maintain security on our future technologies that are vital to national interest, we must recognize and prepare for the threat poised against our technology. Department of Defense policies mandate a high degree of security throughout the acquisition process. However, heightened security awareness and threat-based countermeasures are particularly essential during the research and development phase when our technology is most vulnerable to espionage, sabotage, or exploitation. It is the obligation of each employee or persons involved on this contract be constantly aware of and strictly adhere to security requirements designed to protect sensitive unclassified and other information and resources produced by acquisition, research and development, and technological security efforts outlined in this SOO. The contractor shall ensure employees receive training and follow appropriate Operations Security (OPSEC) measures during the performance of the contract.