Alpha Health and Status Report 16 June 2001

During 6A on GMT 119/19:08:50, C&C3 was moded into Primary in response to a number of "MSD Inaccessible" flags being received from C&C2. C&C3 later malfunctioned, dropping telemetry and communication with the ISS. C&C2 was later brought up as primary. The C&C3 MSD was changed out and has been fully operational since. Investigation continues.

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Crew Reports that both PCS’ they are using have occasional spontaneous reboots and disconnects from the bus. PCS Log files have been dumped and are being analyzed by PCS team. CHIT ISS-0305 has been opened. Investigation continues.

ODIN completed load of INTSYS version 39 software to INT-1 MDM, then transitioned INT-2 to standby in preparation to bring INT-1 on as primary. While both INTs were in standby, a loss of comm with N1-1 was reported by N1-2 and CCS. N1-2 performed a power cycle of N1-1 and N1-1 returned to a nominal state as secondary node MDM. INT-1 is operating nominally with INTSYS version 39. INT-2 is in standby with version 38 still loaded. Several RPC’s appear to have changed states during this event. Investigation Continues.

Under Investigation.

Under Investigation.

The SM Power specialists reported that after analyzing the data obtained during the SM Solar Array Generator test on GMT 2001/093, they suspect that some cables or a part of the solar array/current regulator circuitry may be damaged. This assessment is PRELIMINARY. They will have to further analyze the data and possibly perform more tests to have a complete understanding of the problem. More data will be available as the SM power specialists provide it.

Significance to vehicle: Degraded power production capability in the SM.

Significance to operation: The degree of degradation has not been determined yet, but is not currently impacting SM nominal operations. Further investigation is underway by the Russians. Closure is currently under evaluation for the Russian Anomaly.

On GMT 138/0603, PCU1 was transitioned from Standby with tubes at ~0mmHg to Shutdown. The process was expected to take 4-5 hours, as Latch Valve 1 Closes, Latch 2 Opens, and the gas between (initially at tank pressure) needs to bleed down to less than 1400mmHg (27PSI) before Latch Valve 2 Re-Closes. The expected tube pressure profile was that the pressure would remain at 2500mmHg (50PSI) for roughly 4 hours, then the pressure would exponentially decay to 0mmHg. Latch Valve 1 closed as expected and telemetry confirmed. Latch Valve2 opened, but closed within 10 seconds; the downstream pressure increased to ~2000mmHg (39PSI) confirming the valve did open, but we did not get telemetry feedback that the valve had opened (0.1Hz Tlm). Additionally, the ~2000mmHg was not the expected pressure, as the regulator regulates to approximately 2500mmHg (50PSI). The pressure began the exponential drop to 0 immediately. Analysis of the firmware shows that during the shutdown routine, valve 2 is commanded open, and the line pressure is checked immediately after. The valve has not had sufficient time to open, and therefore the pressure is less than the 27PSI set point. The valve is then commanded closed, without depressurizing the line between the two valves If it is desired to depressurize the line between the two valves, then the following procedure may be used: Command the PCU into Manual Mode, command valve 2 open, wait until the pressure drops below 27 PSI, then reclose valve 2. Power may then be removed from the PCU, or it may be recommended into Shutdown Mode. Safety to recommend a PRACA or a Firmware PR for this issue. Firmware does not properly execute the shutdown function. This is considered a known condition with an operational workaround.

On GMT 140 Russian EPS specialists noticed that the SM Battery 6 had stopped charging and discharging, so they disconnected ZRU #6. Troubleshooting repeated the problem on GMT 144:17:52. Russian EPS specialists believe the PTAB #6 has failed and will need to be replaced. Investigation continues.

VEHICLE INTEGRATION (VI)

At GMT 2001/104:10:43:39, a Zero Cal of the MCA was initiated. It was completed at GMT 2001/104:11:01:59. Subsequent to the Zero Cal and during a break in data between GMT 2001/104:11:09:35 and GMT 2001/104:11:11:009:55, the MCA failed passive BIT Filament (Error Code 33). This condition sends the MCA to STOP with an automatic restart. The MCA performed a successful Active BIT during STARTUP and came up to STANDBY. MOD dumped the MCA data associated with this and it looked fine (No FAIL indication; No C&W indication). BIT Fault data showed nothing. MOD placed the MCA back to OPERATE and it performed satisfactorily. This incident occurred when the Station was away from the South Atlantic Anomaly but during a period of high solar activity. Orbital Science (vendor for the MCA) reported that in the MCA ORU 2 (the MCA part of the MCA) there is a voltage/frequency converter that has a slight susceptibility to EMI. Orbital is concerned that this item may be the reason for the problems experienced by that ORU.

Occurred again at GMT 113/08:07. Same Signature, same status changes. Same nominal start-up after. High Solar activity also noted at this time.

Occurred again at GMT 114/18:55. Similar signature. This caused Brief shutdown of U.S. Element capability to measure O2, N2, CO2, H2O, H2, and CH4. 06/30/01: Plan is to replace MCA electrometer and electronics unit This addresses both problems (MCA electrometer saturation and EMI problems thought to have caused MCA shutdowns). Problem is believed to be leakage through swaged joints on FRIT (flow restrictor). MCA currently operating nominally on filament #2. Indications are that trend toward saturation has slowed significantly, perhaps stopped. Cause of problem either:

For Cause (2) above, the solution would be a design change of a circuit card and a change out of the ORU. PRACA PR# 2681 has been generated.

When reinstalling the Nadir CPAs, specifically when removing the caps from the cable or CPA connectors (they don’t remember which), they noted at least two “EMI tabs” floated out of the connectors. These were very small (1 – 2 mm across) C-shaped pieces of metal. Crew thought they were broken off from an EMI-ring that goes on every connector (?). They captured two, put them on a piece of tape, photographed them, and put them in the “Lost & Found” zip lock bag. No operational impact, possible safety impact during demate due to FOD. Crew should wear eye protection during cable demate. PRACA #2702 has been generated.

On 127/06:38, a Numeric Constraint C&W was set. Data dump of the C&W associated data revealed the following:

5/7/01: The Numeric Constraint bits indicated two procedures have triggered the Numeric Constraint since the last time the associated data was reset. The two are Cmd Validation and Orbit Elapse Time. The Cmd Validation is an expected cause whenever a beta angle of 359.99- 360.00 is sent to the BGA (SPN 18844/1112). The second one has not been seen before. It occurs and is handled within the Determine Orbit Elapse Time procedure. No other algorithms are skipped at a result of this Numeric Constraint. The cause of the problem is tied to the Orbit Elapse Time holding at 6000 for a long time. If the difference between the current time and the Internal Base Start Time (what PVCA believes is the last sunrise) is greater than the defined type range (duration type, S18F14), the error will occur. The largest value the type would hold is 131,072 which is almost 22 orbits. Preliminary data shows the Orbit Elapse Time has been stuck at 6000 for about 24 hours. The Numeric Constraint will stop occurring when the Orbit Elapse Time resets to zero. The Last Orbit Targets Blind mode may not operate correctly, due to the Orbit Elapsed Time It is advisable to not use Autotrack BGA Mode, as the corresponding Blind Mode may not work. clock not counting correctly. It was recommended to PHALCON to place the 2B array in Rate Mode (was in Autotrack) and change the blind mode to Rate. 4B is in Directed Position, which is OK. Investigation:

5/8/01: Data dumps of various locations in the PVCA Memory were performed to give details of the Orbit Elapsed Time function:

5/9/01:

1) The data dumped from PVCUs confirm that the Base Start Time used in the Orbit Elapsed Time calculation is not getting updated properly. The last rise acknowledged by the Orbit Elapsed Time (OET)

calculation was May 5 18:15:14. The calculated (once a second) difference between the Base Start Time and current time is causing the persistent numeric constraint error.

2) The Rise and Set time appear to be updating correctly. Although, a comparison of ODRC values for

Rise/Set from GNC/C&C do not match Rise/Set values dumped from PVCU. They are off by 15 and 23 seconds, respectively. Very puzzling. However, since the Rise and Set times are updating, we can conclude that the Sunlight Status is correctly being determined. Only the Orbit Elapse Time (and those that use it) is affected.

5/10/01: A continuous data dump of the memory locations is being requested to watch the data over two orbits. CHIT 7A-ISS0050 was written to give MOD a procedure to clear the Numeric Constraint Flag and provide advance warning should the same conditions occur that would cause the flag to be set again. CHIT was performed on GMT Day 158, and the Numeric Constraint Flag was successfully cleared.

STS-102 crew reported seeing “lots of small bits of foil floating” inside FM-1 MPLM on ingress. When the MPLM was inspected on de-integration at KSC, a significant amount of debris was observed covering the Air Return Grid (ARG) screen filters. The particles, ranging in size from 1 to 1900 microns, were found to be 30% metallic, 18% organic, 45% organic fiber, and 7% miscellaneous. The fraction of metallic particles is in excess of that found from debris collected after Spacelab missions.

During STS-100, the crew again reported seeing metallic particulate inside FM-2 MPLM on ingress. Upon to return to KSC, ARG screens were again sampled. The amount of particulate was less than for STS-102, but the metallic particle fraction of the contaminant was 45%. The metallic particulate was mostly aluminum for STS-102, and all aluminum for STS-100.

During debriefing, after returning from the ISS, the STS-102 Crew described seeing "lots of small foil floating" inside the FM-1 MPLM on ingress. When the MPLM’s Hatch was opened at KSC an abundance of debris was observed covering the Air Return Grid (ARG) Screen Filters. A PR was taken and all eight (8) screens were cleaned using a flight vacuum fitted with a new filter. Note: these screens were cleaned before M&P visually inspected them but digital images were taken and are on file. The collected debris was submitted to the NASA Lab for analysis to determine its composition.

Results of the Lab’s analysis showed the composition of the debris to be: metallic (30%), red (1%), white (5%), black (1%), white clear (T), amber (T), green (T) and blue (T) materials, along with organic (18%), and organic fiber (45%). The metallic particulate consisted mainly of aluminum alloy. Note: the specific aluminum alloys (6061, 7075, etc.) were not defined. The red materials were composed of RTV and primer. Green and blue materials were paint chips. The black material was composed of 1) carbon steel corrosion products, 2) calcium-chlorine-silica-carbon rich, and 3) molybdenum-sulfur rich materials. White and white clear materials included paint chips, aluminum-chlorine-silica rich and calcium-silica rich materials. The amber materials were made up of aluminum-oxygen rich materials. The particle sizes ranged from 1 to 1900 micrometers.

Debris was also observed on the duel Hatch Seals. It was collected and analyzed to determine its’ composition. Results showed it to be comprised of basically the same components as debris cleaned from the ARG Screen Filters.

Note: a comparison of FM-1 MPLM debris’ composition was consistent with the analysis of debris collected from Space-Lab missions. The only exception being the percentage of metallic particulate. This could be attributed to the last minute work done inside the MPLM installing Racks’ knee braces.

During STS-100 the crew reported also reported seeing metallic particulate inside FM-2 MPLM. Upon return to KSC, M&P performed a visual examination of FM-2’s ARG Screen Filters during ingress. FM-2’s ARG Screen Filters appeared to be similar, though not as dirty, as what was witnessed in the FM-1’s digital images. Another point of interest was the four (4) ARG Screen Filters, adjacent to the install two (2) RSR Racks, contained more debris than the four (4) ARG Screen Filters located by empty bays.

After examination, all eight (8) of FM-2’s ARG Screen Filters were cleaned and the collected debris analyzed like in FM-1. The results were basically the same with the exception being that the percentage of metallic contamination was higher (Ref. 45% vs. 30%) and organic contaminants lower (Ref. 45% vs. 63%) than in FM-1.

An inspection and contamination analysis was also preformed on debris collected from the RSR Racks currently installed in FM-1 for STS-105. All the collected metal particulate sampled turned out to be aluminum alloy. The rest of the debris consisted of black Molybdenum-sulfur rich materials (i.e. dry lube), gray silica-calcium rich materials and yellow paint particles.

All of the samples mentioned above are in M&P’s possession if needed for further analysis. Copies of all NASA Lab analysis are available upon request.

Some potential sources for the contamination found inside the MPLM’s could be:

? Migration into the modules from inside installed RSP, RSR, and Express Racks

? Transfer into modules on orbit from ISS elements/environment

? Present inside the modules from the original fabrication

? Generated during Rack modification &/or routine processing inside the modules

? Created during GSE floor installation/removal

? Migrating in on protective padding, personnel, other GSE

? Coming in from rotation stands/RID during rack installation

? Created by Rack installation/removal during ground processing or on orbit

To my knowledge M&P was never involved in a "base line" cleanliness inspection inside FM-1 or FM-2 MPLM. It should be also be noted that M&P Engineering was not included in the closeout inspection process of neither MPLM’s internal bays nor the installed Racks on STS-102 or STS100 missions.

Due to the contamination concerns, KSC M&P Engineering has implemented a weekly OMI R6900 cleaning inside FM-1 Module. This has already made a noticeable difference in the cleanliness level inside the MPLM. We’ll do the same for FM-2 after de-integration is completed. We’ve also asked that cognizant Systems Engineers included us in the closeout inspection process on internal bay and Racks. Investigation Continues.

Same problem as IFI MER-253 and PRACA 2634. Exp 1 did some cable re-config to disconnect the SM Kurs-P avionics box from the SM forward port (to support FGB-SM docking) and connect it to the SM nadir port (to support DC1 and UDM dockings). Initial self-tests showed a failure of one Kurs set (led to IFI MER-0253 and PRACA 2634). They tried adjusting and re-tightening several connectors, but still saw failure of one set. Additional troubleshooting indicated a bad cable, so the Russians sent up a replacement cable on Progress 4P.

Exp 2 replaced the cable, but then both Kurs sets began to fail the self-tests (led to IFI MER-0399). They tried adjusting and re-tightening several connectors, but still saw failure of both sets. Additional analysis by the Kurs specialists indicated a bad cable configuration left over from previous testing. The crew connected the proper Kurs-P 4AO antenna to the Kurs-P avionics box on 6/6. A Kurs self-test on 6/7 had successful results, with both sets passing the self-test. This IFI Under Investigation.

HSG reported that all went well with manifold 2 but there were problems with manifold 1, either an over or under pressure in the thrusters caused them to shut down and automatically hand over to the SM thrusters. Investigation of this problem continues. SM thrusters will be used for now.

ENVIRONMENTAL CONTROL GROUP (ECG)

The Russians reported that the problem was the Elektron power supply (power cable). They reported that they would command reactivation during their next ground pass; they expected this to be successful; if not successful, there is a spare power cable onboard. At GMT 2001/088:06:41:16, the Elektron Fail indication was reset. During an LOS between GMT 2001/088:13:06 and GMT 2001/088:13:22, the Elektron was deactivated (the Progress vehicle was available for Oxygen supply). As of GMT 2001/102:14:30:00, the Elektron has been operating satisfactorily for several days.

Message sent to MER Moscow requesting part number and serial number. This IFI is under evaluation for closure.

Crew reported the BB2PO fan failure at GMT 2001/94:20:29. The crew removed and inspected the fan. One of the fan blades was damaged. A 2.5 cm piece of debris was found in the vicinity of the fan when inspected. The debris is the most probable cause of the failure. Significance to vehicle: Loss of fan until replaced with another MO-1-5006 fan. Significance to ops: Crew is currently taking the BTK2 fan in the SM and installing it in the place of the failed BB2PO. A 2.5 cm piece of debris was found in the vicinity of the fan when inspected. The debris is the most probable cause of the failure. Fan has been replaced and is operating satisfactorily. To completely restore normal operations, a replacement fan for the BTK2 fan in the CKB2 side of the ventilation system. It is recommended that a PRACA be opened for this problem. P/N and S/N requested from MER Moscow on GMT 2001/150.

John Carr (ECLS) reported the following: Error Code 33 occurred again. MCA went to RESTART. RESTART did not work. For some reason currently not understood, the INT sent a STOP command to the MCA and the MCA went to IDLE. MOD sent a STARTUP NORMAL command and the MCA went to OPEARATE with RAPID SAMPLING of the Lab (MOD did not want the MCA to lose its vacuum.). While in OPERATE, the MCA Location Accessible parameter went from YES to NO. At that time MOD commanded the MCA to STANDBY. The incident appears similar to the incident of last Saturday (GMT day 2001/104) except for the STOP command from the INT and the Location Accessible indicating NO. Problem caused by either:

Proposed solution – for cause (1) above, the solution would be to change the ion pump current limit. For cause (2) above, the solution would be a design change of a circuit card and a change out of the ORU. PRACA PR# 2682 has been generated. S/N#F0002.

During 5A.1 with VRS Vent Valve open, VRS System Pressure was approximately 250 microtorr. This is significantly higher than was observed on 5A. After closing VRS Vent Valve, VRS pressure rise rate was observed to be approximately 218 millitorr/hour. (This compares to a pressure rise rate of approximately 1.86 millitorr/hour after VRS Vent Valve closure during 5A). The "spec" leakage rate for the VRS is 4 x 10exp-4 scc/second. With the spec leakage rate, the VRS System Pressure would rise at a rate of approximately 18.6 millitorr/hour. Pressure rise rate data suggests the VRS was leak-tight during 5A, but may now be leaking. Pressure rise rate of 218 millitorr/hour is roughly consistent with a leakage rate, which would produce 250-microtorr pressures at the VRS CCT with the Vent Valve open. When crew time available (e.g., during 6A stage) disconnect HRF Payload from VRS and cap the VRS QD at this location. Observe whether this eliminates the leak. There is no urgency to do this. There are no payloads, which need to use the VRS through at least 8A. (Although we should do this as soon as conveniently feasible, since if HRF is not the problem, we will have more time to resolve the problem).

Under Investigation.

Under Investigation.

COMMUNICATIONS AND TRACKING GROUP (CTG)

When CAPCOM is talking to the crew in the SM, the ground hears an echo. The ground hears a repeat of their voice. The ISS audio system was configured with S/G 1, ATU Lab 1, ATU Lab2, and RSA 1 in Public Loop1 and S/G 2 ATU Lab 1, ATU Lab 2, and RSA 2 in Public 2. It is probable that the SM audio system was configured in a way that the voice was looped back down the S/G channel.

Forward plan for closure:

OCA_1578 US/RS Comm Configuration procedure was uplinked to the crew to give them an integrated audio config procedure and integrated audio diagram to help them understand the system better. CATO believes that the audio echo is a product of how the RSA1 and 2 lines are connected to SM comm panel 3 and 2 respectively. CATO also wrote OCA 1652 — S-band Troubleshooting. The crew due to a full timeline has not performed it. It will be performed post 5A.1. C&T will write a Chit for on board troubleshooting. Investigation continues.

The VBSP went to self test when commanded to equipment self test, and the equipment self test status was active, Self test was terminated by issuing a deactivate equipment self test command. Upon termination equipment self test, the VBSP did not go to default configuration because it did not start in its default configuration (when the correct self test command is sent to the VBSP, it is expected to return to its default configuration). Currently, the command sent to initiate the VBSP self test command is INCORRECT (see PR15876). In all of our testing, we always ran the self test right after the box was initially powered up – i.e. started in the default configuration, and when it was sent the deactivate equipment self test command, it just returned to where it started. We suspect that’s all it’s doing now returning to the state it started in.

We believe this IFI should be closed because the software will be fixed at Flt 8A with the CCSR2 load. We could probably do some investigative testing at ISIL with the DVTM but we don’t believe that’s really worthwhile because we have a debugging plan referenced above, and the s/w will be fixed at Flt 8A and this won’t be an issue anymore.

When MCOR Activation & Check-out procedure was being performed; on step 7, MCOR had to shutdown due to over temp. MCOR was activated at approx. 101:23:02GMT (6:23 pm CST??). Two minutes later we received heartbeat indication.

Steps 1-6 were completed from the procedures flawlessly. Commands accepted, RT enabled, verification of default configuration and health, documented memory configuration, initiation of BIT test and verification of BIT results. At the step 7 (enabling recording of input channels 4 and 8), the overtemp indication flag came up and MCOR had to shutdown. It happened approximately 45 minutes after activation. Investigation continues. ART will come up with the rational to close this IFI ECD 6/08/2001.

The Early Communication System (EComm or ECS) Starboard Antenna was removed during the 6A EVA2. When the EComm data and power cables were disconnected, part or parts came loose from the cable connectors and floated away. One or more part(s) moved towards the CBM. [IFI 0352 was written to investigate, track, and resolve the Foreign Object or Debris (FOD) situation.] (The EComm Starboard Antenna Assembly P/N is SEG39130674; the Power/Heater cable is P/N SED39129744-301, and the Data/OCA cable is P/N SED39129747-301.) Apparently connector pins and/or screw/bolts were dislodged allowing the connector(s) to emit part(s). The proposed solution is to obtain the culprit cables (power and data) of the returned EComm Starboard Antenna and provide an evaluation and analysis to determine the condition of the cables and connectors, and the likely cause(s) for the connector part(s) coming loose. This IFI can be closed because EComm is GFE, a PRACA should be written to track this issue. The problem is likely a design, manufacturing, or readiness for flight issue. Since the EComm is has been de-commisioned on 6A, the connector design or manufacturing issues are moot. No future use of the EComm is planned for ISS/Station.(Recommend that this IFI be closed via FIAR # ______.) Awaiting return of data and power cables to determine parts missing and to assess cause.

Working with Russians / MER Moscow. This IFI Under Investigation.

As reported by CATO, a “Ku-Band Radiating Beyond Mask” warning was annunciated at GMT 2001/156:18:27:30. As expected the Ku-Band TRC was powered OFF. CATO RTPLOT indicates that TRC PLC went to “Normal” at 156:18:27:31. The Ku-Band PWRL was at -57 dBm when the PLC went to “Normal”. The TRC Xmit Output voltage was at 0 volts (therefore, we did not radiate within the protected Mask. CATO performed CAFN576, Ku-Band Radiating Beyond Mask Corrective Actions, in order to recover the Ku-Band TRC. Investigation continues.

A TD171 to TD171 Single Access handover occurred at GMT 2001/163:09:26:47. Prior to the handover, the Ku-Band system was operating nominally in autotrack mode. After the handover back to TD171 at 163:09:27:07, a TRC Execute function Configuration command was sent at 163:09:28:06 to configure the Ku-Band back to autotrack mode. The command was accepted and the system transitioned to open loop slew then began the spiral acquisition sequence as expected. The TD171 fwd link signal was found during the spiral search and the system transitioned to acquisition lock state with a PWRL of —47 dB, The PLC state transitioned from reset to normal momentarily, but then transitioned back to reset. As a result, the Ku-Band transmitter output power remained at zero. The Ku-Band Antenna was neither near a mask nor did the PWRL value drop below —51 dB at any time after the initial acquisition sequence. The system remained in autotrack mode and continued to track the TD171 FWD link until the end of the TDRS event at 163:09:33:57. The Ku-Band PWRL level remained at a level of —46dB and PLC state remained in reset for the entire event. When the TDRS handover began the TDRS signal strength dropped below the CCS monitored threshold so the C&C MDM commanded the antenna to Pointing Mode Inhibit and PLC to Reset as part of the “Drop Lock” CCS patch. When the handover was complete the CATOs commanded the antenna back to Autotrack, and the antenna successfully locked to the TDRS signal. When the antenna declared lock to the TDRS signal the TRC firmware put the PLC in Normal. At this same time the C&C MDM commanded the antenna back to Pointing Mode Autotrack as part of the CCS “Drop Lock” patch. As a side effect of this command the PLC was taken back to Reset.

Any time the Ku-band losses the TDRS signal, the C&C MDM is going to declare “loss of lock”. Two minutes later, regardless of the state of the antenna, the C&C MDM is going to command the Pointing Mode back to Autotrack. The last CCS commanded state of the PLC will also be included in this command. Every time the Ku-band antenna losses the TDRS signal, the C&C MDM will command it back into Autotrack after two minutes. This command will also include the last state of the PLC which should be Reset when we are in Autotrack. After short (<1 minute) TDRS handovers let the CCS software command the Ku-band antenna back into Autotrack. Investigation continues.

Samples of ITCS fluid were removed from the two operating ITCS loops during flights 5A, 5A.1, and 6A and returned to ground for analysis. The 5A samples showed no ammonia contamination. The 5A.1 samples had an ammonia concentration of 0.03 to 0.05 ppm (estimated due to this level being at the boundary of the detectable limit) in the low temperature (LTL), and the moderate temperature loop (MTL) was 0.09 ppm. The 6A samples have a 0.096 ppm, MTL; and a 0.142 ppm, LTL. The concern is that the trace amounts of ammonia contamination are being introduced to the fluid streams by a “micro-crack” or fissure within the single barrier interface heat exchanger (IHX). A “micro-leak” is not a catastrophic hazard to the crew. Threats to the hardware ( both internal and external) are unknown at this time. Once all possible sources of ammonia contamination are investigated, and if it is determined that the ammonia contamination is from an IHX, then the deficient heat exchanger will need to be removed and replaced by EVA operations. Presently, a spare IHX is stored in the USL. Procedures will have to be developed to remove and replace the IHX. Ammonia contamination in the ITCS fluid could come from: 1) sample bag material/contamination; 2) cabin atmosphere; 3) ground laboratory processing; 4) microbial activity; and/or 5) interface heat exchanger “micro-leak”. A team of engineers/scientists has been formed under the leadership of Cynthia Cross (JSC-EC) and Steve Daugherty (Boeing Active Thermal Control Team). The team consists of representatives from System Safety, Materials & Processes, and Engineering, with specialists in fracture control, chemistry, and fluid hydraulics. A detailed plan is being formulated to investigate potential sources of ammonia contamination. Samples will be taken and returned to ground for analysis at 7A and 7A.1 for trend analysis. It is noted that the quantities of ammonia contamination are “trace” amounts. The ITCS soft materials were tested at an 8.87% ammonia solution by weight ( Reference: Test Report Nonmetallic Material Compatibility with Ammonia , issued by Materials and processes laboratory, Marshall Space Flight Center, date: 10/96) for time periods of 30 and 60 days with all materials in contact with the ITCS fluid showing no significant degradation. 05/30/01: JSC is currently investigating (designing and funding) a test with ITCS fluid in a FEP sample bag to confirm the adequacy of the bag material in preventing ammonia from being absorbed from the cabin atmosphere. Investigation Continues.

Power was removed from the ESP-1 secondary heaters at 2001/116:15:51 and they were left off until it was discovered on day 147. ESP-1 houses a spare PFCS and a spare DSCU. During flight 6A, NCS control was lost and RACU 6 was power cycled at 2001/116:15:51 to remove and reapply power to the N1-1 MDM in an attempt to regain NCS control. The RACU 6 power cycle caused power bus N1RS1 and all its loads to lose power. The 6A N1RS1 Power Bus Repower procedure was missing the ESP heater load on RPCM N1RS1-B RPC 4. Consequently, the ESP-1 secondary heaters were left off until it was discovered on day 147. Also during flight 6A, due to bad NCS data, the DDCU Z1-3B had an NCS software initiated trip at 2001/117:02:13. This caused power to be removed from power buses N13B and N1RS2 and all their loads. The 6A N13B Power Bus Repower procedure was missing the ESP heater load on RPCM N13B-A RPC 3. Consequently, the ESP primary heaters were left off unti