KC-135_CCR_SOO.pdf

KC-135 Centering Cylinder Assembly Redesign

STATEMENT OF OBJECTIVES (SOO)

FOR

KC-135 CENTERING CYLINDER ASSEMBLY REDESIGN

BACKGROUND:

The KC-135 MLG Centering Cylinder Assembly (CCA), current configuration NSN

1650-01-582-2429, Part Number 200733824-10, (note, that the legacy configuration is still in use in field as well as an oversized version of both the legacy an current, for a total of 4 configurations) is a closed hydraulic positioner that maintains the Main Landing

Gear (MLG) truck in the level position, relative to the MLG strut during gear extension, stowage and retraction. The CCA has an extensive history of leaking and/or pressure loss which leads to field unserviceability problems and eventually to premature turn-in and costly depot repair. The current CCA design has a service life that insufficient for the typical 5 year Periodic Depot Maintenance (PDM) cycle of the KC-135 aircraft.

An improvement project was implemented in 2015 but preliminary field reports indicate that the improvement project was inadequate in resolving the issues plaguing the CCA.

The previous improvement effort identified the ingress of contaminants and seal damage due to dithering as the leading causes of premature CCA failure. The improved design introduced a plug to reduce internal corrosion and wear by preventing the ingress of water and other contaminants. Energized PTFE cap seals were also introduced to the design for improved wear resistance. However, there have been 40 Product Quality

Deficiency Reports (PQDR) against the Centering Cylinder as well as numerous user complaints since fielding the improved design.

Preliminary analysis indicates that the new plug unintentionally causes any hydraulic fluid and nitrogen that has bypassed the piston seal to be trapped in the non-functional cavity of the positioner causing the CCA to seize. This seizing failure mode is referred to as hydro-locking (HL) and prevents practical removal of the Centering Cylinder from, and frequently leads to damage of, the mating components. Furthermore, these HL failures have been attributed to in-flight aborts due to MLG retract failure. Of the 40

PQDR’s, 29 reports indicate leaking and/or HL as the failure mode of the CCA.

The improved CCA also incorporated an improved gauge assembly that was intended to seal better and provide easier to read visual indication of the CCA internal pressure. The issues observed with the gage assembly are water or other contaminants in the gauge viewing window, leaking form the gauge, broken gauge needles and inaccurate gauge readings. This new gauge assembly has been the cause of 11 out of the 40 total PQDR’s.

The CCA currently has a Mean Time Between Demand (MTBD) of 2,710 hours and experiences a Not Repaired This Station (NRTS) rate of 130 annually. The Main Landing

Gear Brake Snubber which is a similar item in the same operational environment experience much lower repair rates (a MTBD of 6,536 hours and a NRTS rate of 59 annually). It is unknown if the CCA failures are generated by normal usage, depot or field processing/tooling, inadequate inspections or testing, inadequate design/components, etc.

A solution is needed in order to mitigate the consistent on-aircraft failure of the CCA during normal service and extend the reliability of the CCA in order to assure proper function for a minimum of the typical 5 year PDM cycle.

PRIMARY OBJECTIVES:

The purpose of this task is to seek engineering services in support of resolving current

Reliability, Availability, and Maintainability (RAM) issues with the CCA. In general, the resolution is envisioned to include all non-recurring engineering activities required to provide and implement an improved configuration or full redesign and/or identify manufacturing or overhaul processes or methods required to prevent premature failure of the CCA thus providing a solution that will allow the CCA to last a minimum of 5 years on-aircraft.

While not all tasks may be funded and/or exercised depending on the level of effort required to correct the reliability issues, they shall all be included in the ROM, along with associated pricing for each task. This will allow the Government the flexibility to achieve the optimal solution as the project progresses.

TASK 1 - PROGRAM ECONOMICS/DEFICIENCY IDENTIFICATION:

The contractor will provide engineering services to determine program economics with a recommended funding and detailed implementation strategy, including all aspects of IPT involvement (including, but not limited to: KC-135 users, KC-135

SPO, MAJCOMs etc.) from cradle-to-grave. The contractor will identify all current reliability/performance weaknesses as well as perform an analysis on each. These shall address areas and/or root causes of leaking, hydro-locking, in-flight aborts, other premature failure modes, corrosion, wear, processing, assembly methods, etc.

Deliverables:

1. Analysis of Alternatives with respect to resolving identified weaknesses, including evaluation of the currently understood problems and assumptions about causes and potential solutions. Draft implementation strategies shall be included for each alternative.

2. Economic Analysis for potential alternatives including materials evaluation and return on investment (ROI).

TASK 2 - PRELIMINARY DESIGN REVIEW (PDR):

The contractor will generate PDR documentaion which outlines the recommended design solutions, process improvments, preliminary analysis, and conceptual level

Technical Data Package (TDP). An initial Modified Airworthiness Certification

Criteria Compliance Report (MACC-CR) shall be delivered which provides all necessary qualification testing and analysis for certification.

1. PDR documentation

a. Briefing materials

b. Meeting minutes

c. Action items

2. Preliminary Analysis:

a. Analysis reports and analysis computer generated files will be per

USAF drawing 201612106. Analysis reports and computer generated analysis files will be delivered to the 417 SCMS/GUEA with unlimited rights.

b. Any other data, engineering tools, or computer files used or developed in this engineering effort will be delivered. Including, but not limited to, source code, spreadsheets, script files (i.e.

Matlab, Mathcad, etc.), macros, databases, scanned documents, copies of referenced materials, video, photos, and audio.

3. AOA and EA Update

a. Analysis of Alternatives, including all assumptions, justifications, and methodologies used.

b. Economic Analyses, including all assumptions, justifications, and methodologies used to demonstrate economic viability.

4. Conceptual level TDP per MIL-STD-31000

5. Initial MACC-CR

TASK 3 - CRITICAL DESIGN REVIEW (CDR):

The contractor will generate CDR documentation which will include but not be limited to: material changes, processing requirements/improvments, developmental design drawings, and final (SPO approved) MACC. Structural analysis will be performed to prove CDR design airworthiness.

1. CDR documentation

a. Briefing materials

b. Meeting minutes

c. Action items

2. Analysis:

c. Analysis and analysis computer generated files will be per USAF drawing 201612106. Analysis reports and computer generated analysis files will be delivered to the 417 SCMS/GUEA with unlimited rights.

d. Any other data, engineering tools, or computer files used or developed in this engineering effort will be delivered. Including, but not limited to, source code, spreadsheets, script files (i.e.

Matlab, Mathcad, etc.), macros, databases, scanned documents, copies of referenced materials, video, photos, and audio.

3. Updated Implementation Plan

a. Updated Analysis of Alternatives outlining the final solution with all assumptions, justifications, and methodologies used to down-select the final solution from other alternatives, including structural, economic, logistical, and reliability/maintainability considerations.

b. Updated Economic Analyses outlining the final solution with all assumptions, justifications, and methodologies used to demonstrate economic viability.

c. A detailed Integrated Product Team (IPT) master plan of all steps, milestones, factors, and required forms and approvals for advancement from design through implementation.

4. Developmental level TDP per MIL-STD-31000

5. Final MACC-CR

TASK 4 - PROTOTYPE MANUFACTURE AND QUALIFICATION BY

TESTING:

Upon CDR approval, the contractor will generate a qualification test plan (QTP), procure test assets, perform a test readiness review (TRR), perform validation testing, perform qualification testing and generate a qualification test report

(QTR).

1. Qualification Test Plan (QTP)

2. Test Readiness Review (TRR)

a. Briefing materials

b. Meeting minutes

c. Action items

3. Qualification Test Report (QTR)

6. Final Analysis (re-performed as necessary based on qualification testing and FEA validation):

e. Analysis reports and analysis computer generated files will be per

USAF drawing 201612106. Analysis reports and computer generated analysis files will be delivered to the 417 SCMS/GUEA with unlimited rights.

f. Any other data, engineering tools, or computer files used or developed in this engineering effort will be delivered. Including, but not limited to, source code, spreadsheets, script files (i.e.

Matlab, Mathcad, etc.), macros, databases, scanned documents, copies of referenced materials, video, photos, and audio.

TASK 5 - IMPLEMENTATION AND TECHNICAL DATA:

The contractor will assist the government with approval efforts for the

Configuration Control Board (CCB). The contractor will also provide all necessary technical documentation for the manufacture, repair and overhaul of any redesigned components. The contractor will also continue engineering and logistics support to the IPT for the process outlined in the implementation master plan described above. Additionally, the contractor will provide the Government with a minimum of six (6) prototype parts per the CCB approved technical data package and support validation and verification of technical orders, assembly processes, and fit-check of the component into the next higher assembly and aircraft.

1. CCB documentation, including all Airworthiness documentation

2. System Safety Evaluation

3. Type 2D Production level TDP per MIL-STD-31000

4. Technical Order (T.O.) source data in Word (.doc) and Adobe PDF (.pdf) format, along with Standard Generalized Markup Language (SGML) for

Aircraft System T.O.s, as required by the KC-135 System Program Office

(SPO). Illustration files will be delivered in Computer Graphics Metafile

(.cgm), vector images with a minimum resolution of 300 DPI, or as required (e.g. .TIFF, vector).

5. Stress Manual updates (if required)

TASK 6 – FIELD SERVICE EVALUATION

The contractor will provide the Government with two Field Service Evaluation

(FSE) shipsets utilizing the CCB approved technical data package. A shipset is defined as the full CCA assemblies necessary in order to retrofit one complete aircraft with the new design. The contractor will prepare and coordinate all required documents and support activities necessary for completing an FSE of the redesigned CCA. The FSE period shall be for a minimum of twelve months. The contractor will provide support to the FSE location including all hardware, supplies, and documentation. Technical support will be provided during the FSE period to resolve any issues that arise. All issues identified during the FSE shall be addressed through updates to the TDP and source data. Depending on the impacts of the design change(s) for the CCA as well the significance of any issues identified during the FSE, at the end of the FSE a final CCB may be required prior to full implementation to present the results of the FSE and gain approval for the final configuration. The contractor will assist the government with any approval efforts required for the final CCB.

1. FSE articles

2. FSE Test Plan

3. In-progress FSE Status Reports

4. Final FSE Report

5. Updates to all tech data as required including:

a. Type 2D Production level TDP per MIL-STD-31000

b. 3D models in SolidWorks compatible format

c. Technical Order (T.O.) source data in Word (.doc) and Adobe PDF

(.pdf) format, along with Standard Generalized Markup Language

(SGML) for Aircraft System T.O.s, as required by the C-5 System

Program Office (SPO). Illustration files will be delivered in Computer

Graphics Metafile (.cgm), vector images with a minimum resolution of

300 DPI, or as required (e.g. .TIFF, vector).

d. Stress Manual updates (if required)

6. Final CCB documentation, including all Airworthiness documentation (if required)

QUALITY ASSURANCE:

To insure that performance objectives are met, monthly status reviews for this project and effort will be held at which time the contractor must provide cost, schedule, performance accounting and reporting in the form of customer defined quad-charts.