Reaction Control System

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Section 21 Reaction Control System
. . . Michael McCullough Swales Aerospace, Inc.
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Contents

• System Overview
• Test Verification Matrix
• Component and Subsystem Level Testing
• System Level Testing
• Subsystem Level Reviews
• Status of Launch Site Procedures
• Status of Launch Site GSE
• Open Problem Records and Residual Risk
• System Readiness

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Reaction Control System
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EO-1 RCS Performance Requirements

• Documented in SAI-SPEC-110, released March 27,
  1997
• Propellant capacity 22.3 kg
• System mass not to exceed 11 kg
• Thrusters provide velocity control for S/C
• Thrusters provide attitude control authority
  during D V
• Thrusters meet performance specification of OAC
  MR-103G
• System must meet requirements of EWR 127-1

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Verification Matrix
21 - 5
6
Accumulated Power On Time for EO-1 S/C
Components
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RCS Verification Matrix Items

• Alignment - by Analysis
• Thruster alignment maintained by control of
  manufacturing tolerances
• Static Load - Qualification by Similarity
• Proof Pressure - Test
• Proof Pressure Tests conducted at component and
  subsystem level
• Mass Properties - Weighed
• Weighed at the subsystem level including Zenith
  Deck
• Interface Verification - Test
• Interfaces tested during spacecraft IT process
• Functional - Test
• Tested at the component and subsystem Level

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RCS Component Verification

• Propellant Tank
• Determination of Volume
• Proof Pressure Test
• Internal and External Leakage Test
• Radiographic/Penetrant Inspection
• Visual Inspection and Cleanliness
• Fill/Drain Valves
• Inspection and Cleanliness
• Proof Pressure
• Internal and External Leakage
• Operational Cycles
• Filter
• Proof Pressure Test
• External Leakage
• Bubble Point and D-P
• Visual Inspection and Cleanliness

• Latch Valve
• Internal and External Leakage Test
• Operating Cycles
• Visual Inspection and Cleanliness
• Vibration
• Thrusters
• Hot Fire Performance
• Proof Pressure, Vibration
• Internal and External Leakage
• Pull-In and Drop-Out Voltage
• Visual Inspection and Cleanliness
• Pressure Transducer
• Vibration and Proof Pressure Test
• Calibration
• Electrical Characteristics

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RCS Verification at Primex

• System Welds
• Leak Checked, Dye Penetrant and Radiographic
  Inspection
• Proof Pressure Checks
• High Pressure Proof Pressure Test (820 psig)
  excl. Tank
• Complete System Proof Pressure Test (480 psig)
• Internal Valve Leak Checks
• Thruster and Latch Valve Seats Checked
  Individually
• Electrical Component Resistance and Isolation
  Checks
• System Level Functional Checks
• Thrusters, Latch Valve, Pressure Transducer and
  Thermostats

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RCS Checks at Swales

• Electrical Component Resistance and Isolation
  Checks
• System Integration with Spacecraft
• System Level Functional Checks
• Pre- and Post-Integration
• Thrusters, Latch Valve, Pressure Transducer,
  Thermostats and Thermistors
• Thruster Phasing with Gas Flow at 15 psig

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RCS Environmental Test Program

• The EO-1 RCS was fully integrated with the
  spacecraft for Shock, Vibration and Acoustic
  Testing
• RCS Functionality verified during CPT 5
• arcs1.prc - exercised thruster valves
• arcs2.prc - powered catalyst bed heaters
• arcs3.prc - exercised the latch valve
• RCS Integrity verified during Pressure Transducer
  Calibration and Valve Leak Checks
• Thermal Vacuum / Thermal Balance Testing Verified
  Proper Operation of the RCS Thermal Control
  System.
• Temperatures maintained between 18C-24C during
  cold case tests
• No heater activity during hot case testing

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RCS Thermal Control (1)
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RCS Thermal Control (2)
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RCS Pressure Transducer Calibration

• End-to-end Test Performed, Propellant Tank to
  Ground System Display
• No Change in Scale Factor
• 100 psi/volt
• Offset Adjusted by 1.3 psi
• No Hysteresis
• 2 Counts Maximum Error
• 0.2 FS
• Calibration will be repeated as part of Launch
  Site Processing

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RCS Internal Leak Check

• Performed Internal Leak Check on All RCS Valves
• Series Redundant Valve Seats Checked Individually
• Checked At MEOP (320 psig)
• Total of 9 Valve Seats Checked
• System Level Performance is Acceptable
• Leak Check of Fill/Drain Valves Added to System
  Level Test in Response to RFA 14.27
• Next System Flight Level Pressurization Test
  Planned as Part of Launch Site Processing

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RCS Pressure Cycle Log
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Technical Peer Reviews

• Series of Requirements and Design Reviews
  Conducted at Primex Aerospace
• Attended by SAI Lead Engineers for Mechanical,
  Electrical, Stress and Thermal Subsystems, QA,
  S/C Systems, and Program Manager
• EO-1 RCS Requirements Review
• January 21-22, 1997, Primex Handout 97-H-2355
• EO-1 RCS Preliminary Design TIM
• April 3-4, 1997, Primex Handout 97-H-2376
• EO-1 RCS Critical Design Review
• June 3-4, 1997, Primex Handout 97-H-2391
• EO-1 RCS Pre-Ship Review
• March 3, 1998, Data Package P/N 33400-965

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PSR RFA Status

• Three RFA Issued During EO-1 Spacecraft Pre-Ship
  Review
• RFA 14.17
• Completed
• RFA 14.27
• Completed
• RFA 14.28
• Completed

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RFA 14.17

• Specific Request RCS valve leakage criteria
  should be revised lower (100 scc/hr is too high)
  and leak rate for out of spec valve should be
  trended.
• Supporting Rationale I believe any valve leaking
  at 100 scc/hr is so far out of family that it
  should be replaced. If the out of spec valve
  remains stable, it is probably OK. However, if
  its leak rate increases significantly, it should
  be replaced.
• Project Response Valve leak rate acceptance
  criteria revised downward to 30 scc/hr. Leakage
  in excess of this rate shall be cause to review
  flight worthiness and launch site latch valve
  usage. SAI-PROC-309 revised to reflect new leak
  rate criteria and capture requirement for review
  of launch site procedures.

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RFA 14.27

• Specific Request Leak test fill and drain valves
  (at least primary seals)
• Supporting Rationale Cycling fill and drain
  valves on the ground can potentially introduce
  contaminants into seals and cause leakage. Leak
  testing valves requires minimum resources and
  time and adds significant assurance to mission
  success.
• Project Response SAI-PROC-309 has been revised
  to include a leak check on RCS fill and drain
  valves. This test will be conducted at the Range
  as part of the next scheduled RCS valve leak
  check.

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RFA 14.28

• Specific Request Perform a post environmental
  leakage test on the propulsion system.
  Recommendation pressurize with GN2 to TBD psia
  monitor pressure decay for longest duration
  possible.
• Supporting Rationale
• 1. The integrity of the welds, lines, components
  of the propulsion subsystem has not been verified
  after being stressed by environmental tests.
• 2. Discovery of leakage during propellant loading
  ops is much too late in the timeline. Leakage
  after loading hydrazine poses safety hazard to
  personnel.
• 3. With the delay in launch schedule, monitoring
  pressure for decay test may be feasible over 3-4
  months.
• Project Response The RCS has been pressurized to
  40 psi (maximum allowed by DOT regulations) and
  pressure decay is being monitored. Pressure
  decay check will continue through until
  propellant loading, approximately two months.

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Failure Free Operation Time

• No failures of RCS encountered during S/C IT
  program
• Total operating time
• Pressure transducer powered on with S/C
• Thruster and latch valve actuation limited to
  select ACS phasing and S/C comprehensive tests
• No configuration changes required
• No changes required in Test Plan
• No hardware or software changes required

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RCS Launch Site Procedure Status

• Two procedures considered hazardous by NASA/KSC
  and air force 30SW - review and approval required
• RCS checkout and leak test procedure SAI-PROC-309
• Hazardous due to pressures involved
• Submitted to range for comment
• Comments incorporated
• Ready for final range review approval
• EO-1/SAC-C propellant loading procedure PAC
  IP-0645
• Hazardous due to propellants and pressures
  involved
• Submitted to range for comment
• Comments incorporated - TIM held to discuss
  details
• Final approval contingent on facility selection

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RCS Ground Support Equipment Status

• Propellant loading cart has been demonstrated
  using PAC Procedure IP-0645
• Pressure test console and all associated
  equipment has been calibrated and / or
  proof-tested and will remain valid throughout the
  launch campaign
• Portable pressure monitor unit has been
  functionally demonstrated
• All export / ITAR issues associated with SAC-C
  propellant loading have been resolved
• SCAPE / PHE and Interscan training will be
  accomplished shortly after arrival at the launch
  site
• Range safety has reviewed GSE design documented
  in the EO-1 MSPSP SAI-SFTY-019 submitted to the
  range 10/26/99
• Previewed by range safety prior to official
  submittal

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RCS Statement of Readiness

• The EO-1 Reaction Control System is ready for
  launch site processing
• System integrity, performance and functionality
  has been demonstrated
• The EO-1 RCS Launch Site Procedures are ready for
  launch site operations
• Procedures have been demonstrated using GSE
• There are no obstacles to procedure approval by
  the Western Range
• The EO-1 RCS GSE is ready to support launch site
  processing
• Primex is ready to support EO-1 / SAC-C
  propellant loading

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Problem Records and Residual Risk

• Problem Records
• No Critical Problem Records
• No Open Problem Records
• Residual Risk Items
• None
• Potential Redbook Items
• None

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Special Topic Leak Rate in RCS Valve
. . . Michael McCullough Swales Aerospace, Inc.
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Thruster Valve Leakage

• History - During RCS thruster valve leak checks,
  one thruster (4) displayed unexpectedly high
  leakage through the downstream valve seat. 13
  scc/hr observed, 1 scc/hr expected.
• Possible Cause - Valve seat contamination,
  perhaps catalyst fines.
• All testing has been performed with positive gas
  flow during thruster valve cycling
• Catalyst beds are below valve seats, limits the
  opportunity for contaminants to percolate down
  into valve seats

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Thruster Valve Leakage

• Ramifications for EO-1 Mission
• Gas leak rates as high as 30 scc/hr still
  represent a liquid tight seal. This seat is still
  functional
• Thruster valve assembly (two seats) displays
  zero gas leak rate, redundant liquid seals
• Redundant thruster valve seat not required by
  range safety
• If thruster valve leak rate exceeds 30 scc/hr,
  The thruster valve shall be considered failed and
  thruster reliability is reduced from 0.9966 to
  0.9956 For a 3 year mission
• Corrective Actions
• Thruster valves exercised (with gas flow) during
  CPT5
• Individual valve seats will be tested at the next
  opportunity, when the RCS is again cycled to MEOP
  of 320 psia.

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Thruster Valve Leakage

• Conclusion
• Failure of any individual valve seat, latch valve
  or thruster valves, on EO-1 has been considered
• Should any valve seat (thruster or latch valve)
  exceed 30 scc/hr gas leak rate, planned launch
  site activities shall be reviewed with respect to
  this loss of redundancy