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HMI Reliability

HMI Reliability

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HMI Reliability

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  1. HMI Reliability Dale Wolfe Reliability Engineer LMSSC*ATC*LMSAL 650-424-3030

  2. HMI Reliability • Requirements for HMI Reliability are derived from the SDO HMI Product Assurance Implementation Plan, 2H00021 • The following HMI reliability analyses are SDO MAR related deliverables covered by DID 4.2 • EEE Parts Stress Analysis (PAIP 4.3.2) • Reliability Prediction & Reliability Block Diagram (PAIP 4.3.3) • Failure Mode and Effects Analysis & Critical Items List (PAIP 4.3.1) • Limited Life Items (PAIP 4.3.4)

  3. EEE Parts Stress Analysis • The stress analysis was performed at the most stressful part parameters that can result from the specified performance and environmental requirements. • Stress analysis results are compared to EEE-INST-002 derating guidelines and documented in 2H00233, Rev A, “EEE Parts Stress and Derating Analysis • Those parts that were determined to exceed their derating limits were resized, redesigned, or removed from the system • Currently no parts exist in the HMI Instrument that exceed the derating limits of EEE-INST-002

  4. Reliability Block Diagram • HMI Reliability Block Diagram (full instrument)

  5. Reliability Block Diagram • HMI Reliability Block Diagram (degraded instrument) Not required

  6. Reliability Prediction • The reliability prediction calculates the probability of success for the HMI instrument over the 5-year mission. • The HMI Reliability Prediction and Reliability Block Diagrams are documented in 2H00032, Rev A. • Failure rate calculations are primarily derived from MIL-HDBK-217F • Mechanism failure rates are derived from similar mechanisms on-orbit experience and life testing • Changes from the PDR reliability calculation include the incorporation of RAL CEB reliability numbers, update in mechanism cycling and use of vendor failure rates for Actel FPGAs. • This resulted overall in a slightly higher HMI reliability calculation from PDR

  7. FMEA and Critical Items List • An FMEA is a procedure by which the ways an item or function can fail (failure modes) are identified and the effects of the failures on performance (failure effects) and mission objectives (severity) are evaluated. • The following severity categories are used in the FMEA for each failure mode.

  8. FMEA and Critical Items List • Failure modes that affect the SDO or HMI mission adversely, category 1, 1R, 1S and 2 are identified on a Critical Items List. • The critical items list is maintained within the FMEA where a risk mitigation approach is listed for each item. • The FMEA and Critical Items list is documented in HMI document 2H00229, Rev A.

  9. Critical Items List

  10. Limited Life Items • Limited Life items are defined as those items that are time or cycling sensitive in nature and whose expected useful life is less than twice the required life • The limited life items are maintained in the HMI FMEA, document 2H00229 • Mitigation actions are identified in the limited life items list to minimize potential risk in meeting mission requirements and provide confidence in their use for the duration of the HMI mission.

  11. Limited Life Items

  12. Summary • All EEE components meet the derating requirements of EEE-INST-002 • Reliability calculations and Reliability Block Diagram are prepared based on the latest HMI design and are documented • No category 1 single point failures exist in the HMI instrument • Category 2 single point failures are documented in the Critical Items List • The Power Subsystem single point failure will be addressed prior to the build of the flight model HMI • Limited Life items are identified and risk mitigation is documented