# Presentation: 754803

## Section 5

_***Section 5***_
***Probabilistic Risk Assessment***

*** ******. . . Ron Duphily***
*TRW Space & Technology Division*

## Failure Severity Criticality Categories for FMEAs

***Severity criticality codes for these FMEAs are defined as follows: ***
***1)******	******Effective loss of the Mission (non-recoverable complete loss of ALI data) ***
***2)******	******Loss of the Hyperion Mission (non-recoverable complete loss of Hyperion data)***
***3)******	******Serious degradation, but still meets some of the Level I ALI and/or Hyperion requirements***
***4)******	******Some degradation or operations impact, but still achieves the baseline mission***
***5)******	******Little or no impact to mission success or mission operations***
***Some examples are:***
***Category 1:  Power System, ACS, WARP, or ALI instrument dying completely***
***Category 2:  Hyperion instrument failing by itself***
***Category 3:  A Hyperion ASP failure, or an X-Band Phased Array failure***
***Category 4:  Heaters***
***Category 5:  PPT, GPS, AC, etc.***

**Failure Severity Criticality Categories for FMEAs**

## EO-1 Minimal MissionReliability Block Diagram

****** ****= Failure Rate in Failures per Billion Hours**

- = Has  Consequence Category 1 from FMEA

**Attitude Control**
**Subsystem**
**(ACS)**

**Electrical Power**
**Subsystem**
**(EPS)**

**Communications**
**Subsystem (CS)**

**Command & Data**
**Handling**
**Subsystem**
**(C&DHS)**

**Reaction Control**
**Subsystem (RCS)**

**ALI**

**WARP**

**0.9490**

**0.9679**

**0.9535**

**0.9638**

**0.8960**

**0.9846**

**Reliability @ 1 year = 0.7447**
**Failure Likelihood   = 0.2553**

**Has Redundancy**

**0.9999**

## Attitude Control Subsystem (ACS)Reliability Block Diagram

****** ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**ACS LVPC**

**ACE RSN**

**ACE I/O**

**Prop I/O**

**RWA (x3)**

**Coarse Sun**
**Sensors (3)**

**Magnetic**
**Torquer**
**Bars (MTB)x3**

**Three Axis**
**Magnetometer**
**TAM**

**Autonomous**
**Star Tracker**

**IRU (3 Gyro’s)**

******=400**

******=650**

******=800**

******=1670**

******=1609**

******=390**

******=408**

**Reliability @ 1 year = 0.9490**
**Failure Likelihood =0.0510**

******=48**

**FMEA ID   6.4**

**FMEA ID   6.1**

**FMEA ID   6.2**

**FMEA ID   6.3**

**Redundant Thruster**
**Valves & Cat Bed Heaters**

**FMEA ID  8.0**

**FMEA ID  11.0**

**FMEA ID 12.0**

**FMEA ID 13.0**

**Update IRU Data with**
**TAM & Ground Op’s**
**Interventions**

**FMEA ID 9.0**

**FMEA ID 10.0**

## Electrical Power Subsystem (EPS)Reliability Block Diagram

****** ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**PSE RSN**

**PSE LVPC**

**Power Output**
**Module #1**

**Battery**
**(21/22 cells-Short)**
**(22/22 cells-open)**

**Battery Charge**
**Module**

**Battery Enable**
**Relay Box**
**(BERB)**

**Power Output**
**Module #2**

**SADA Motor &**
**Electronics**

**Solar Array**

**Solar Array**
**Module**

**Solar Array**
**Release (HOP’s)**

**Yoke/SADA**
**Hinge**

******=650**

******=400**

******=900**

******=900**

******=110**

**Redundant windings & Electronics**

**Reliability @ 1 year = 0.9679**
**  ****Failure Likelihood = 0.0321**

**FMEA ID 1.7**

**FMEA ID 1.11**

**FMEA ID 1.9**

**FMEA ID 1.10**

**FMEA ID 1.6**

**FMEA ID 1.1**

**Redundant Strings**

******=636**

**Triple-redundant relays**

**FMEA ID 1.4/1.8**

**Redundant Batt Temp**

**FMEA ID 1.5**

**FMEA ID 2.2**

**Outside panel has power **

**Redundant HOP’s**

**FMEA ID 3.0/1.2 **

**FMEA ID 1.3**

**FMEA ID 2.1**

**R=.9999678**

**R=.9999726**

**R=.9999878**

**R=.9994829**

**R=.9995**

## Command & Data Handling (C&DH)  Reliability Block Diagram

****** ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**Reliability @ 1 year = 0.9638**
**  ****Failure Likelihood = 0.0362**

**FMEA ID 5.1**

**FMEA ID 5.2**

**FMEA ID 5.3**

**FMEA ID 5.4**

**Redundant Fiber**
** ****Optic Harness**

**Redundant**
**Star Coupler**

**Redundant Data**
**Bus Controller**

**R=.9999907**

**R=.9999878**

**R=.9999726**

## Communications Subsystem (CS)Reliability Block Diagram

****** ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**S-Band**
**Transponder**
**and Diplexer**

**Omni**
**Antennas (2)**

**3 db Hybrid**

**20 db**
**Directional**
**Coupler**

**X-Band**
**Modulator**
**(RF Exciter)**

**X-Band**
**Phased Array**
**Antenna**

**X-Band RSN**

******=5430**

**Reliability @ 1 year = 0.9535**
**  ****Failure Likelihood = 0.0465**

**FMEA ID 15.1**

**FMEA ID 15.2**

**FMEA ID 15.3**

**FMEA ID 15.4**

**FMEA ID 14.9**

**FMEA ID 16.1.1**

**FMEA ID 16.1.2/16.1.3/16.2/16.3/16.4**

**Test port**

**Not credible failure**
**R= 1.0**

**Failure not credible**
**R=1.0**

**Use S-Band as backup**

**Use S-Band as backup**
**Redundant RT tranceiver**
**Loss of 1/2 of XPAA elements OK**

**Use S-Band as backup**

## Reaction Control Subsystem (RCS)Reliability Block Diagram

**Prop I/O**
**(from ACS)**

****** ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**FMEA ID 6.3**

**Propellant**
**Tank Press.**
**Transducer**

**Hydrazine**
**Thruster &**
**Valves **

**Thruster**
**Cat Bed**
**Heaters**

**Hydrazine**
**Latch**
**Valve**

**FMEA ID 7.4**

**FMEA ID 7.3**

**FMEA ID 7.2**

**FMEA ID 7.1**

**Redundant valves**

**Redundant Heaters**

**Tank Press. TLM  not required**

**Failure to open is**
** ****category 3**

**R=.9999963**

**R=.9999981**

**R=.9999726**

**Reliability @ 1 year = 0.999967**
**  ****Failure Likelihood = 0.000033**

## WARP  Reliability Block Diagram

**RS-422 Input**

**LVPC/RSN**

**Processor**

**Memory**
**Interface**

**Memory #2**

**Memory #1**

**RF Exciter**

**Duty Cycle = 10%**

******=Failure Rate in Failures per Billion Hours**

**= Has Consequence Category 1 from FMEA **

******=1120**

******=1940**

******=4541**

******=4131**

**Reliability @ 1 year = 0.8960**
** ****Failure Likelihood  = 0.1040**

**Duty Cycle = 12%**

**FMEA ID 14.2 & 14.3  **

**FMEA ID 14.4**

**FMEA ID 14.5**

**FMEA ID 14.6**

**FMEA ID 14.7 & 14.8**

**FMEA ID 14.9**

**Use S-Band backup mode**

**Power**
**Filter Box**

******=300**

**FMEA ID 14.1**

**R=.99565**

******=7790**

## ALI  Reliability Block Diagram

******  ****= Failure Rate in Failures per Billion Hours**

- = Has Consequence Category 1 from FMEA

**FPA**
**(4 SCA’s)**

**Focal Plane**
**Electronics**
**(FPE)**

**Mechanisms**

**ALI Control**
**Electronics**
**(ALICE)**

**Radiator**
**Heater**
**& Sensors**

**Focal Plane**
**Heater &**
**Sensors**

**Outgas**
**Heaters**

**Telescope**
**Heaters**

**Calibration**
**Lamps**
**5%DC 1/2 Stdby**

******=906**

******=840**

**Reliability @ 1 year = 0.9846**
**   ****Failure Likelihood = 0.0154**

**FMEA ID 17.1**

**Redundant**

**FMEA ID 17.2**

**FMEA ID 17.3**

**Redundant Launch Latch**
**Backup cover opening mechanism**

**FMEA ID 17.4**

**FMEA ID 17.5**

**Redundancy**

**FMEA ID 17.6**

**Use Bar heater &**
**Sensor as backup**

**FMEA ID 17.7**

**Use radiator, Bar heater**
**& sensor as backup**

**FMEA ID 17.8**

**FMEA ID 17.9**

**Degradation of data**

**Degradation of data**

**R=.9999929**

**R=.9997966**

**R=.9999969**

**R=.9999969**

**R=.9999512**

## Hyperion Reliability Block Diagram

- DC/DC
- Converter

- Analog Board

- Clock Bias Board

- Digital Board

- Focal Plane
- Electronics

- DC/DC
- Converter

- Analog Board

- Clock Bias Board

- Digital Board

- Focal Plane
- Electronics

- Cryo Cooler &
- Electronics

**SWIR**

**VNIR**

- Cover Motor
- & Bearings

- Motor/ Heater
- Drive Board

- Microprocessor

- Data
- Formatter

- DC/DC
- Converter

- Telemetry Board

**HEA**

- =300

- =25

- =47

- =65

- =400

- =1430

- =300

- =25

- =47

- =65

- =400

- =183

- =100

- =950

- =200

- =300

- =100

******=Failure Rate in Failures per Billion Hours**

**Reliability @ 1 year = 0.9839**
**Failure Likelihood =0.0161**

- = Hyperion single point failure

## EO-1 FMEA Category 1 Failure Probabilities

**EO-1 FMEA Category 1 Failure Probabilities**

## Hyperion Unit Failure Probabilities

**Hyperion Unit Failure Probabilities**

##  EO-1 FMEA Category 1R Failure Probabilities

## 0.75

**0.75**

**@ 4 mos = 0.90 for Minimal Mission**

## PRA Summary

***Reliability at 1 year for FMEA Category 1 = 0.7491***
***Reliability at 1 year for FMEA Category 1R = 0.9941***
***Redundant 1R items have small impact on reliability***
***Reliability at 1 year for Category 1 & 1R = 0.7447***
***If 1R items were not redundant then R = 0.6917***
***Category 1 single point failures are primary drivers of residual risk.***
***Completing Minimal Mission in 4 months has acceptable failure probability of 10%.***