sts-27 national space transportation system mission report

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NSTS-23370

STS-27 National SpaceTransportation SystemMission Report

February 1989


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TABLE OF CONTENTSTitle Page

INTRODUCTION 1MISSION SUMMARY 1SOLID ROCKET BOOSTER PERFORMANCE 3EXTERNAL TANK PERFORMANCE 33PACE SHUTTLE MAIN ENGINES PERFORMANCE 3ORBITER PERFORMANCE 3

MAIN PROPULSION S UBSYSTEM 4REACTION CONTROL S UBSYSTEM 4ORBITAL MANEUVERING SUBSYSTEM 4POWER REACTANT AND STORAGE DISTRIBUTION SUBSYSTEM 5FUEL CELL POWERPLANT SUBSYSTEM 5AUXILIARY POWER UNIT SUBSYSTEM 5HYDRAULICS/WATER SPRAY BOILER SUBSYSTEM 6ENVIRONMENTAL CONTROL AND LIFE SUPPORT SUBSYSTEM 7AVIONICS SUBSYSTEMS 7COMMUNICATIONS AND TRACKING SUBSYSTEM 7TELEVISION SUBSYSTEM 8MECHANICAL SUBSYSTEMS 8AERODYNAMICS 9THERMAL CONTROL SUBSYSTEM 9THERMAL PROTECTION SUBSYSTEM 9


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INTRODUCTION

The STS-27 National STS (Space Transportation System) Program Mission Reportcontains a summary of the vehicle subsystems activities on this twenty-seventhflight of the Space Shuttle and the third flight of the OV-104 vehicle(Atlantis). The STS-27 flight was a classified Department of Defense mission,and as such, the classified portions of the mission are not presented in thisreport. The sequence of events for this mission is shown in Table I. Thisreport also summarizes the significant problems that occurred during the STS-27mission. The problem tracking list is presented in Table II to provide acomplete list of all Orbiter problems that occurred. Each of the Orbiterproblems are discussed in the body of this report.

M IS SI ON S UM MA RY

The Space Shuttle vehicle was successfully launched from Launch Complex 39B atthe Kennedy Space Center (KSC) on December 2, 1988, with solid rocket booster( SRB) ignition o ccur ring at 337: 14:3 0:33 .987 G. m.t. (08: 30:3 3.98 7 a.m .c.s .t.) .Data indicate that all subsystems performed satisfactorily.The crew for this twenty-seventh flight of the Space Shuttle were Robert L.Gibson, Commander; Guy S. Gardner, Pilot; and Richard M. Mullane, Jerry L.Ross, and William M. Shepard, Mission Specialists.The launch was delayed approximately 24 hours because the winds aloft were, ontwo occurrences, higher than the limits. On the second attempt, the launch wasagain delayed because the winds aloft were higher than limits. However,subsequent balloon data showed the winds were receding such that the conditionswould reach a load of 102 percent. Prelaunch analysis indicated that vehicle


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temperature sensor 2A reading (below 130 OF) and a violation of the launchcommit criteria. A waiver was approved and the countdown was continued.The launch phase was satisfactory in all respects. No Orbiter subsystemanomalies were noted during ascent. A two-engine orbital maneuvering subsystemfiring was performed satisfactorily after MECO at 337:15:13:08.9 G.m.t., and theduration was 214.6 seconds.The crew discovered approximately two gallons of free water in the environmentalcontrol and life support subsystem bay shortly after wake-up on flight day 2.The free water was caused by a problem with the humidity separator B (FlightProblem STS-27-04). The crew switched to humidity separator A and thenim plemented es tab lish ed clean -up p roc ed ures .The crew reported, at 338:11:25 G.m.t., that the text and graphics system (TAGS)printer had a paper jam that resulted in the loss of the TAGS for the remainderof the mission (Flight Problem STS-27-06).The left and right reaction control subsystem (RCS) helium regulator and heaterlegs were switched from A to B at approximately 339:14:26 G.m.t. About 6 hourslater, RCS activity caused the right oxidizer B leg regulator outlet pressure todrop to about 236 psia (Flight Problem STS-27-08). At that time, the crewswitched to the A leg on the right RCS. The A leg regulator locked up at 253psia and operated properly.The flight control system (FCS) checkout and the RCS hot-fire test were satis-factorily completed on flight day 4 in preparation for entry. Auxiliary powerunit (APU) 3 was used for the checkout.All preparations for entry were completed and the 211.2-second deorbit maneuverwas completed satisfactorily at 341:22:33:05.2 G.m.t. The entry was normal inall respects, and because of the Tracking and Data Relay Satellite - West, datawere received throughout most the period of normal blackout. After completing a


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SOLID ROCKET BOOSTER PERFORMANCE

All SRB systems performed as expected. The SRB prelaunch countdown was normaland no SRB or solid rocket motor (SRM) problems were identified. There were nolaunch commit criteria (LCC) violations associated with the SRB.The performance of both SRB's was near predicted values and well within theallowable performance envelopes. Data also indicate that SRB separationsoccurred at the predicted times. Reports of visual sightings from the recoveryships indicate that the deceleration subsystems performed as designed, and bothSRB's were floating in the spar buoy mode.

E XTE RNA L T AN K P ERF ORM AN CE

All objectives and requirements associated with the external tank (ET) supportof the launch were met. There was one ET LCC violation, a nose-cone temperaturethat was 40.7 of (LCC states 45 of to 135 OF), and this condition was caused byimproper operation of the ET nose-cone purge. The nose-cone temperaturesviolated the minimum LCC for approximately 2 hours. The LCC waiver for thisc on dition w as ac cep ted .All ET electrical and instrumentation systems performed satisfactorily.

SPACE SHUTTLE MAIN ENGINES PERFORMANCE

All Space Shuttle main engine (SSME) parameters appeared to be normal throughoutthe prelaunch countdown, comparing well with prelaunch parameters observed on


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MAIN PROPULSION SUBSYSTEM

The main propulsion subsystem (MPS) performance was nominal. The poppet/sleeveclearances of the gaseous oxygen flow control valves (FCV) were reworked to the0.0010- to 0.0012-inch range for the STS-27 mission. As a result, the transientsluggish FCV operation seen during STS-26 was not repeated.A topping valve showed simultaneous open and closed position indications duringthe MPS dump and the first vacuum inerting procedure (Flight Problem ST5-27-03).Following the first vacuum inerting procedure, the hydrogen manifold pressureincreased more rapidly than expected, to a value of 19 psi. This condition isindicative of a possible malfunction of the liquid hydrogen repressurizationsystem (Flight Problem STS-27-13). The vacuum inerting procedure was performeda second time with satisfactory results.The liquid hydrogen fill/drain valve response was slow and out of specificationthree of the four times the valve was actuated (Flight Problem STS-27-24).Procedural changes instituted for STS-27 were successful in avoiding theerroneous master alarms experienced during the STS-26 entry purge/manifoldrepressurization operation. Additional changes are being made for subsequentmissions to establish a plan for caution and warning system management in caseof a 750-psia regulator failure during the entry configuration procedures atdeorbit maneuver ignition minus 25 minutes.

REACTION CONTROL SUBSYSTEM

The performance of the reaction control subsystem (RCS) was nominal. Oneanomaly was noted in the right RCS oxidizer B leg regulator, which had a lockupshift and responded slowly during ET separation and subsequent usage (Flight


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valve appeared to fail as indicated by a gaseous nitrogen storage tank pressurerise of about one-half that normally seen during dual-coil operation (FlightProblem STS-27-11). This condition did not impact any future OMS firings.STS-27 was the first flight for the revised B-leg keel web heater thermostat.The operation was nominal with the RCS tank temperature and fluids beingmaintained above the zot limits.

POWER REACTANT STORAGE AND DISTRIBUTION SUBSYSTEMThe power reactant storage and distribution subsystem (PRSD) performedsatisfactorily. At lift-off, the PRSD subsystem contained 2337 lb of oxygen and268.1 lb of hydrogen, of which 1100 lb of oxygen and 130 lb of hydrogen weresupplied for the fuel cells and 39 lb for use as breathing oxygen. No problemwas noted with the PRSD subsystem. Reactants remaining at touchdown wereadequate to provide a 92-hour mission extension capability at average powerlevels.

FUEL CELL POWERPLANT SUBSYSTEMThe three "operational improvement configuration" fuel cells performed aspredicted and fulfilled all electrical requirements throughout the mission. Theaverage total Orbiter electrical power and load was 14.6 kW and 476 A,respectively. The fuel cells produced 1540 kWh of electrical energy andoperated for approximately 187 hours. The fuel cells were shutdown 43 hoursa fte r l an di ng .The fuel cell 2 alternate water line temperature cycled erratically between 100and 125 of after the line heaters were switched from A circuit to B circuit.(Flight Problem STS-27-12). The normal operating band is between 70 and 90 of.


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measurement (T-1) was biased 40 to 50 of higher than T-2 temperatures duringentry o peration s (Fligh t Pr ob lem STS-27-01d) .During the APU pre-start period prior to descent, it was noticed that the crewprocedures pocket checklist left the APU controllers on after the pre-startcheckout. The controllers remained on for about 35 minutes before APU 1 wasstarted and for about 30 minutes before APU 2 and 3 were started. Because ofthe possibility of an inadvertent start signal being generated from a failure inthe controller when the power is on, a change will be submitted to the pocketchecklist to require controller power be turned off after pre-start checkout.A hydraulic load test was performed after landing to ensure full recovery of theAPU's when put under a high load. The APU's responded nominally with chamberpressures over 1200 psia. The run times and fuel consumption for the APU's aresummarized in the following table.

Ascent FCS c heck ou t Descent TotalAPU Run Consump- Run Consump- Run Consump- Run Consump-time, tion, Ib time, tion, Ib time, tion, Ib time, tion, Ibmin. min. min. min.1 19.9 52.0 0.0 0.0 85.6 155.0 105.5 207.02 19.9 51.0 0.0 0.0 57.7 130.0 77.6 181.03 19.8 56.0 6.1 15.0 57.7 137.0 83.6 208.0

HY DR AU LI CS /W ATE R SP RA Y B OI LE R S UB SY ST EMThe hydraulics/water spray boiler subsystem performed satisfactorily during allphases of the mission. A launch commit criteria requirement was violated whenthe system 2 water spray boiler ready signal was lost 23 minutes before APUstart. LCC requirements specify that a water spray boiler ready signal be


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The system 2 accumulator pressure lagged main pump pressure at APU activation by15 seconds during the ascent phase and by 5 1/2 minutes during the descentphase. When bootstrap pressures reached the main pump pressure, the reservoirand accumulator pressures tracked each other satisfactorily (Flight ProblemSTS-27-14).

ENVIRONMENTAL CONTROL AND LIFE SUPPORT SUBSYSTEMThe environmental control and life support subsystem (ECLSS) performance wasnominal except for the failure of humidity separator B and cabin temperaturecontroller 2.The humidity separator B failed to flow water to the waste water tank (FlightProblem STS-27-05). Approximately two gallons of water were found on and underthe middeck floor. Humidity separator A was used satisfactorily.During the cabin temperature controller reconfiguration, cabin temperaturecontroller 2 was non-responsive and the actuator could not be moved manually(Flight Problem STS-27-09). A change was made back to cabin temperaturecontroller 1 which operated satisfactorily for the remainder of the mission.A out-of-tolerance condition was noted in the air revitalization pressurecontrol system oxygen flow transducer on system 1 (Flight Problem STS-27-01c).The transducer was toggling past the specification limit value of 0.25 lb/hr.The condition is understood and was of no consequence to the mission.

A VI ON IC S S UB SY ST EM SAll avionics subsystems operated satisfactorily with only minor anomalies noted.

a. The rudder surface position indicator appeared to be biased 4 degrees


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the first time. Handover operations improved continuously with only minorhandover delays. Because of TDRS-C (West), the normal 15- to 20-minute communi-cations blackout period during entry lasted only 2 minutes, and this occurrednear the 300,000-foot altitude.Problems noted were as follows:

a. TACAN 1 did not lock correctly during prelaunch powerup (Flight ProblemSTS-27-17). Recycling of the power switch resulted in proper operation.

b. Text and graphics system printer paper feed jammed and the system wasnot used for the remainder of the mission (Flight Problem STS-27-06). A totalof 46 pages were successfully transmitted prior to the failure.

c. Ku-band channel 2 operations recorder dumps could not be completedwithout channel 3 activated. (Flight Problem STS-27-15).

d. One of the crewmen (MS-2) reported a light shock when the headsetinterface unit (HIU) was used with sweaty skin. This occurred both on theground and during flight operations (Flight Problem STS-27-19).

T EL EV IS IO N S UB SY ST EMThe television (TV) subsystem provided very satisfactory video communicationsthroughout the mission, although some minor problems were noted:

a. During startup, television monitor 1 showed a fault light, but thelight did not remain on after recycling the power (Flight Problem STS-27-20).

b. Television camera A focus would not drive and the crew reported athumping noise emanating from the drive mechanism (Flight Problem STS-27-20).


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The left ET umbilical door ready-to-latch indicator 2 failed to indicate on(Flight Problem STS-27-02). The door latched properly with the remaining twolat ch i nd ic atio ns .The brakes performed as expected. The brakes were removed and inspected with novisual damage noted.

AERODYNAMICS

All aspects of the vehicle aerodynamics were satisfactory with nominalperformance in the areas of angle of attack, side slip, and elevon and body flappositions. No problems were noted in the aerodynamics area.T HE RM AL CO NTR OL S UB SY ST EM

The thermal control subsystem functioned satisfactorily. During the prelaunchphase of the mission, all temperatures were at nominal values, and no heatersystem or thermal instrumentation failures occurred. However, several thermalanomalies were noted during the on-orbit phase of the mission. One heatersystem failed, and this was APU 2 gas generator bed heater system A (FlightProblem STS-27-04). The alternate heater system B was used and successfullymaintained all components within acceptable temperature limits. Six "dithering"thermostats were observed. This phenomena has been observed on all previousflights of the Shuttle and is not considered a problem.One thermal sensor failure (V46T0140A) occurred (Flight Problem STS-27-01a) onthe APU 1 exhaust vent. Several sensors appeared to be biased by as much as45 of . These were APU 1 gas generator bed temperature (V46T0122A) (FlightProblem STS-27-01b), and APU 1 gas generator valve module temperature (V460171A)( Fl ig ht Pr ob le m ST S- 27 -0 1d ).


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between hardened and annealed. The door also had a small buckle. There was atotal of 707 impact sites with 298 having a major diameter of equal to orgreater than 1.0 inch. The number of impact sites was the most experienced onany flight. There were only eight impact sites on the left-hand side of theOrbiter.An AFRSI-covered fiberglass carrier panel was lost from the right-hand OMS pod(V070-396403-002). The Koropan on the door looks excellent and this isattributed to the panel being located in a lower heating area. The panel lossis attributed to possible improper installation.

GOVERNMENT FURNISHED EQUIPMENT

The government furnished equipment operated very satisfactorily, however someminor discrepancies were noted:

a. Several of the Volume H door fasteners could not be reinstalled (FlightProblem STS-27-18a).

b. The wet trash door and access hatch were sticky when opening andclosing (Flight Problem STS-27-18b).

c. The foot restraints of the toilet were difficult to deploy and stow andappeared to be galled (Flight Problem STS-27-18c).

d. The Shuttle portable onboard computer stopped working briefly duringthe mission (Flight Problem STS-27-18d).

e. The galley dispensed 25 percent more water than required. Also, thepackage retention device had an in-place lever problem (Flight ProblemSTS-27-18e).


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DETAILED TEST OBJECTIVES/DETAILED SUPPLEMENTARY OBJECTIVESThe following detailed test objectives (DTO)/detailed supplementary objectives(DSO) for the STS-27 mission are unclassified and have been accomplished.NumberDT0301DDT0305DDT0306DDT0307DDT0308DDT03llDDT0623

DT0783

DT0784DT0786DS0450DS0458DS0466

DS0467

TitleAscent Structural Capability EvaluationAscent Compartment Venting EvaluationDescent Compartment Venting EvaluationEntr y Stru ctural CapabilityVibration and Acoustic EvaluationPOGO Stability Perf orman ceCabin Air Monitoring

Secure CCTV System Test

Space Ground Link System NavigationCertificationText and Graphics System TestSalivary Cortisol Levels During Acute Phase

o f SpaceflightS aliv ar y A ceta min op hen Ph ar ma co kin etic sVariations in Supine and Standing Heart Rate,

Blood Pressure and Cardiac Size as aFunction of Spaceflight Duration and TimeAfter the FlightInfluence of Weightlessness on BaroReflexFunction

Activit~ StatusData only MetData only MetData only MetData only MetData only MetData only MetSamples of MetOrbiter atmos-phere

Met

Data only MetMetMetMetMet

Met


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TABLE 1.- STS-27 SEQUENCE OF EVENTS

Event Description Actual time,G.m.t.

APU activation

SRB HPU activation

Main propulsionSystem startSRB ignition command

(lift-off)Throttle down to96 percent thrust

Throttle down to65 percent thrustMaximum dynamic

pressure (q)Throttle up to104 percent thrustBoth SRM's chamber

APU-1 GG chamber pressureAPU-2 GG chamber pressureAPU-3 GG chamber pressureLH HPU system A start commandLH HPU system B start commandRH HPU system A start commandRH HPU system B start commandEngine 3 phase in effectEngine 2 phase in effectEngine 1 phase in effectSRB ignition command to SRBEngine 3 vehicle commandEngine 2 vehicle commandEngine 1 vehicle commandEngine 3 vehicle commandEngine 2 vehicle commandEngine 1 vehicle commandDerived ascent dynamicpressureEngine 3 vehicle commandEngine 2 vehicle commandEngine 1 vehicle commandLH SRM chamber pressure

337:14:24:30.27337:14:24:33.15337:14:24:36.33337:14:30:06.287337:14:30:06.237337:14:30:06.751337:14:30:06.751337:14:30:27.436337:14:30:27.549337:14:30:27.677337:14:30:33.987337:14:30:53.957337:14:30:53.949337:14:30:53.958337:14:31:02.437337:14:31:02.429337:14:31:02.438337:14:31:41337:14:31:31.878337:14:31:31.879337:14:31:31.879337:14:32:33.791


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TABLE 1.- CONCLUDED

Event Description Actual time,G.m.t.3g accelerationMECOET separationAPU deactivation

OMS-2 ignition

OMS-2 cutoff

Flight controlsystem checkoutAPU startAPU stopAPU activationfor entry

Deorbit maneuver

Total load factorMECO command flagMECO confirm flagET separation command flagAPU-1 GG chamber pressureAPU-2 GG chamber pressureAPu-3 GG chamber pressureLeft engine bi-prop valvepositionRight engine bi-prop valvepositionLeft engine bi-prop valvepositionRight engine bi-prop valveposition

APU-3 GG chamber pressureAPu-3 GG chamber pressureAPU-1 GG chamber pressureAPU-2 GG chamber pressureAPU-3 GG chamber pressureLeft engine bi-prop valvepositionRight engine bi-prop valveposition

337:14:38:01337:14:39:08337:14:39:08337:14:39:26337:14:44:24.42337:14:44:25.57337:14:44:26.42337:15:13:08.9337:15:13:08.7337:15:16:43.4337:15:16:43.2

340:16:50:28.84340:16:56:31.71341:22:24:37.82341:22:52:29.94341:22:52:31.04341:22:29:34.2341:22:29:34.0


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PROBLEMTRACKINGLIST DATE PAGt5TS-27/0V104 FINAL REPORT ~-8-89 1NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.

5T5-27 Instrumentation: W. Scott-01 a) V46T0140 APU 1 EGT#2 a) 337: 14:42 a) The auxiliary power unit (APU) 1 a) MMACS- X39032erratic. CAR27RF08 exhaust gas temperature 2 02 D. CorcoranCRIT2R3 measurement (V46T0140) became X33329erratic after Main Engine Cutoff(MECO). Later, the measurementfailed open. Postflighttroubleshooting confirmed thetransducer failure.Corrective Action: The transducerF1asbeen removed and replaced.Failure analysis will be tracked by CAR27RF08. This isa criticality 2R3measurement. Closed. F/A tracked byCAR27RF08.

b) V46T0122 APU #1 GGbed temp. b) Prelaunch b) The auxiliarrc power unit (APU) 1 b) MMAC5- W ScottBias45F high. CRIT3/3 ~as generator GG) bed temperature 01 X39032V46TO 122) had a high bias during D. Corcoranprelaunch operations. The bias was X33329approximately 45 Fhigh at GGbedtemperatures of 3500F. The bias wasnot present after APU start during thefinal prelaunch activities.Corrective Action: This bias isconsidered acceptable. No correctiveaction isrequired. This isa criticality3/3 measurement. Closed.

c} 02 flow system 1 & 2 transducers c) Oxygen flow transducer c) EECOM- H. Rotterbias c) 377: 19:00 measurements 1 and 2 (V61R2105A 01 X39249CRIT3/3 and V61R2205A) were biased high D. Corcoranand toggling just above the X33329specification value of 0.25 1b/hr.Corrective Action:TFlisbias isconsidered acceptable. Nocorrective action is required. This isacriticality 3/3 measurement. Closed.JS( form 318 (feb 81) NASAJSC


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--.J

PROBLEMTRACKING LIST STS-27/0V104 fiNAL REPORT DAft PAC,E~-8-89 2

NO. TITLE TIME COMMENTS MOD NO. RESP.MGR.

STS-27 Instru mentation:-01 d) APU #1 GGvalve module T-1 temp d)337:05:16 d) The auxiliary power unit (APU) 1 W. Scottbiased CRIT2R3 GGvalve module T-1 temperature X39032measurement (V46T0171A) was D. Corcoran

biased 40 to 50 Fhigher than the T-2 X33329temperature measurement which was98 Fduring entry.Corrective Action: This bias isconsidered acceptable. No correctiveaction is required. This isa criticality2R3measurement. Closed.

e) MADS RCCchin temperature e) The modular auxiliary data system G.SalazarV09T9889A erratic e) Reentry (MADS) reinforced carbon carbon x30162CRIT: NONE (RCC)chin temperature measurement D. Corcoran(V09T9889A) became erratic during x33329entry. Postflight troubleshootingcould not reproduce the anomaly.The temperature transducer andassociated wiring check out withinspecification.Corrective Action: No correctiveaction required. This is adevelopment measurement and hasno flight criticality. Closed.

NASAJSCJSCform 318 ( feb 81)


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PROBLEMTRACKING LIST STS-27IOV1 04 FINAL REPORT OATE PAGE~-8-89 3NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.STS-27 left ETumbilical door ready to latch 337: 14:48 During closure of the external tank MMACS-03 N. Jevas-02 Indicator #2 (V56X3542X) indicated CAR 27RF02 (ET)doors, the left umbilical door X38950

off/should be on. CRIT 3/ 3 reedy-to-latch indicator 2 J . Guthery(V56X3542X) indicated "off" when it X33306should have indicated "on". Correctindications were received for latches1 and 3 and the door latchednormally. Testing at KSCreproducedthe failure. Upon inspection, abroken connector was found; theshell over the electrical wires wasbroken between the motor controlassembly and the latch mechanism.Two bare wires were exposed whichlater shorted and blew the associatedfuses.Conclusions: The left ETumbilicaldoor ready-to-latch indicator 2 faileddue to a broken connector whichcaused a subsequent short and blownfuses.Corrective Action:The broken connector has beenremoved and replaced. Closed. F/Awill be tracked by CAR 27RF02.Criticality 303.

JSCForm 318 (feb 81) NASAJSC


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-tC

PROBLEM TRACKING LIST STS-27 /OV1 04 FINAL REPORT DATE PAGE~-8-89 4NO. TITLE TIME COMMENTS MODNO. RESP. MGR.

5T5-27 lH2 topping valve (PV13) showed 337: 14:42 The MPS topping valve closed BSTR-01,03 P. Cota-03 simultaneous open/closed indications CAR 27RF03 indication microswitch (V41X1456X) X39037during dump & vacuum inert. CRIT 3/3 indicated closed when the valve was S. McMillanpowered o~en and the open X35913indication V41X1453E) indicatedopen during MPS dump. When openpower was removed, both indicationsstayed on. When the valve wasmanually powered open duringvacuum inert, both indications stayedon. When the switch removed powerat the end of vacuum inert, the openindication was lost and only a closed

indication remained (the correctposition).Corrective Action:KSCTroubleshooting perPR-MPS-4-04-0449. Did not repeatproblem. Valve removed andreplaced. OV103 monitor duringground servicing. Closed. CAR27RF03. Criticality 3/3.STS-27 APU #2 GG heater system malfunction. 337:21 :35 APU 2 GG bed heater system A failed MMACS-05 W. Scott.-04 CAR 27RF07 to respond when switched on. Heater X39032CRIT 1R3 system B was selected when GGVM S. McMillantemperatures were observed to be X35913below 60"F and falling. The GG bedheater system Bt hen appeared to failON at MET 00: 19:20:00. The crewturned heater system B off.Subseduently heater liB II was turnedon an operated properly.Corrective Action:KSCTroubleshooting per IPR30RV0030 and chit J2866. Verifiedheater switch failure. KSCR/R SW. onA-12 panel per PR-EPD-551. Closed.

CAR 27RF07 CRIT 1R3JS{form318(feb81) NASAJS(


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PROBLEMTRACKING LIST STS-27/0V104 FINAL REPORT UAlt PAGE~-8-89 SNO. TITLE TIME COMMENTS MOO NO. RESP.MGR.5T5-27 Humidity separator "B" flooded. 338:13:44 Shortly after wakeup on the second EECOM- E.Winkler-05 CAR27RFOl flight day (338: 13:44 G.m.t.), the 02 X39244Crit.2R3 crew reported that about two gallons D. Dillmanof free water was discovered in and X31733around the ECLS5bay. Water

appeared to be coming fromhumidity separator B. Waste waterquantity showed a correspondingtwo-gallon deficit compared topredictions. The crew performed in-fl ight maintenance to clean up thefree water and switched to humidityseparator A which performednormally for the remainder of themission.Both the OV-104 and OV-103 (5T5-26)humidity separators were removedand sent to the vendor for testing.The OV-104 humidity separator Bwasfound to be non-functional due to aclogged pitot tube which preventedliquid water from being pumped outofthe unit. OV-104 humidityseparator A functioned withinspecification.OV-l03 humidity separator Bfunctioned within specification. TheOV-103 humidity separator A wasdegraded (6 percent water carryovervs. 1 percent specified). Check valveleaks are also suspected in OV-103humidity separator A and may becontributing to its degradation.Disassembly of this unit to determineactual component failure is in processat the vendor.

JS( form 318(feb81) NASA,SC


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to.:)-

PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAGER-8-89 6NO. TITLE TIME COMMENTS MOD NO. RESP. MGR.

5TS-27 Humidity separator B flooded. Corrective Action: EECOM- E. Winkler-05 (Concluded) Spare humidity separators were 02 X39244placed on board OV -103 and OV -104. D. DillmanClosed. CAR 27RF01. Criticality 2R3. X31733STS-27 TAGS paper jam and TAGS OHC status 338: 11 :25 At about 338: 11 :25 G.m.t., while INCO-02 W.R. Richards-06 change at image start. 338:01 :52 receiving and processing Text and INCO-03 X30203FIAR-JSC EE Graphics System (TAGS) Mode 1 D. Suiter646 images, the TAGS hardcopier X33339CRIT 3 experienced a paper ~am. Attemptsby the crew to clear t e jam using theTAGS in-flight maintenance tool wereunsuccessful. The TAGS hardcopier

was powered off and the Teleprinterwas utilized for all subsequent uplinkmessage traffic during the mission.There was no adverse effect on themission.At about 338:01 :52 G.m.t., whileconfigured in the READY state, theTAGS hardcopier spontaneouslychanged its status to STANDBY as anew message transmission began.The hardcopier was immediatelyreconfigured to READY and uplinkmessage transmission continued.There was no mission impact and theanomaly did not recur during theflight.Corrective Action:The TAGS was removed, andreplaced. Closed. F/A tracked onFIAR-JSC-EE-646. Criticality 3.

NASA-J5CJ5CForm 318(Feb81)


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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DAn 'AGE~-8-89 7NO. TITLE TIME COMMENTS MODNO. RESP. MGR.

STS-27 a) TPSDamage Ascent a) Post landing tile examination J. Smith-07 CAR 27RF13 revealed approximately 250 tiles with X38860CRIT 111 damage greater than 1 inch in area. J. GutheryMost impact dama"e on right -side X33306bottom of wing & uselage.250-300tile. R/R; KSCestimate. Probablecause SRB Nose Cone Debris. Closed.CAR 27RF13. Crit icali ty 101.b) ROMS carrier panel missing CAR 27RF09 b) ROMS carrier panel missing. J. SmithCRIT 1/ 1 Corrective Action: X38860Post flight inspection revealed bolts J . Gutheryin place, but no washers installed. X33306Incorrect installation. Closed. CAR27RF09. Critical ity 111.c) TACAN #2 lower L-band antenna CAR 27RF 12 c) Antenna overheated due to J. Smith

over temp. CRtT 1R3 missing TPSt ile on Orbiter lower X38860surface. This condition was J. Gutherydetermined by postflight thermal X33306analysis.Corrective Action:Remove and Replace antenna.Closed. CAR 27RF12. Criticality 1R3.STS-27 Right RCSoxid. "B" He regulator slow 339:14:27 After SWitchin~ from the helium" A" PROP-01 G. Grush-08 response CAR 27RF10 regulators to t e "B" regulators, the X39030CRtT 1R3 aft right Reaction Control System T. Welch(RCS)oxidizer tank pressure X33335decreased from 249 to 242 psi. Whenswitched back to the" A" regulators,the RCSoxidizer tank pressure rose toa nominal 249 psi.A helium blowdown test wasperformed on the "B" regulators byKSCwhich confirmed the lowpressure regulation.Corrective Action:The regulator has been removed andreplaced. Closed. F/A tracked byCAR 27RF10. Criticali ty 1R3.

JSCForm )18 (Feb 81) .

No

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PROBLEMTRACKING LIST STS-27/0V104 FINAL REPORT OATt PAGE~-8-89 8

NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.5T5-27 Cabin temp. controller #2 non 339: 14:30 At approximately 339: 14:30 G.m.t., EECOM-03 E.Winkler-09 responsive CRIT3 the crew reported that the motor for X39244

cabin temperature controller 2 was D. Dillmanfrozen and would not move when the X31733cabin temperature controller switchposition was changed from controller1to controller 2. During the 4 to 5minutes that controller 2 wasselected, its actuator did not movefrom its original position and thecrew reported that the actuator feltmechanically bound up. The crewthen switched back to the originalcabin temperature controller 1whichperformed normally for theremainder of the mission. The cabintemperature controller 2 motor wasretested at KSCand performednominally.Corrective Action:A crew procedure change isplannedto alert the crew to the time requiredfor the temperature controller toreach its normal operating position.Closed. Fly asis. Criticality 3.

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PROBLEMTRACKING LIST STS-27/0V104 FINALREPORT DATE PAGt2-8-89 9NO. TITLE TIME COMMENTS MODNO. RESP.MGR.

STS-27 Ku Band boom stow indicator #2 341:03:49 During KU band stow, boom stow MMACS-06 M. Schmalz-10 malfunction (V54X0022E) indicator #2 did not function X30131properly. D. SuiterCorrective Action: X33339Deleted as flight problem transfered to Data review isolated problem toMCC-Ol ground data processing. Problemtransferred to MCC-01: STSOCDR091909,IPR30RV-0034. Closed..~STS-27 Left OMS GN2 isolation valve coil The left Orbital Maneuvering System PROP-02 J. Hooper-11 failure CRIT1R3 (OMS)aaseous nitrogen (GN2) tank X39031showe a pressure rise from coil heat T. Welchof about one-half of the rise normally X33335seen. Troubleshooting at KSC

revealed no anomalies in the valve orpower to the valve. Review of dataindicates this was seen on previousflights. No impact during themissions.Corrective Action:None. Closeo. Criticality lR3JSC fOf"m318 (feb 81) NASA-JSC


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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAGE2-13-89 10NO. TITLE TIME COMMENTS MOONO. RESP.MGR.STS-27 FCP#2 alternate H20 line erratic CAR27RF14 The fuel cell 2 alternate water line EECOM-04 F.Plauche-12 temperature. CRIT3/3 temperature cycled erratically x 39034between 100 and 125 Fafter the line D. Dillmanheaters were switched from the" A" X31733circuit to the "B" circuit at

approximately 339: 15: 16G.m.t. Thenormal control range is 70 to 900 F.The erratic behavior ceased when theline heaters were switched back tothe" A" circuit. Potential causes ofthis problem were isolated to eitheran erratic thermostat "B" or a smallleak in the alternate water line checkvalve which allowed a trickle flow ofhot water through the lineTroubleshooting at KSCcould notduplicate the problem, with thethermostat "B" controlling withinspecification and the alternate waterline check valve exhibiting noleakage.Corrective Action:The thermostat has been removedand replaced. Failure analysis will betracked via CAR27RF14 Closed.Criticali ty 3/3

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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAG~2-8-89 11NO. TITLE TIME COMMENTS MOONO. RESP.MGR.STS-27 LH2 dump manifold pressurization Post MEea At 337: 14:41: 12 G.m.t., after BSTR P.Cota-13 response eRIT: initiation of the main propulsion -01 x 39037

Nominal 3/ 3 system (MPS) liquid hydrogen (LH2) S.McMillanAbort 1 dump, the liquid hydrogen 17- inch X35913feedline manifold pressure begandecreasing from approximately 51psia. When this pressure reached 20psia approximately 20 seconds later,the LH2manifold repressurizationsystem should have begun flowingregulated helium at approximately 20psia into the manifold. However, themanifold pressure continued to drop,reaching a value of 17 psia about 57seconds after dump initiation. At thistime, the manifold pressure suddenlyincreased and remained at 21 psiauntil commanded off. The LH2manifold repressurization systemincludes two 2-way solenoid valves(LV42, 43) which provide seriesisolation of the MPS pneumaticregulated helium supply from the 20-psi regulator. The valves arecommanded open by the generalpurpose computers at the start of theMPSdump. Helium flow into themanifold is subse~uently controlledby the 20-psi regu ator (PR6) , which isreferenced to the manifold throughan external sense line. Helium flowinitiation isconfirmed by thesimultaneous increase in thepneumatic helium supply pressuredecay rate and the GH2pressurization systempressure.

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NV1

PROBLEMTRACKING LIST STS-27/OV104 FINAL REPORT DAn PAGE12-8-89 12NO. TITLE TIME COMMENTS MOONO. RESP.MGR.5T5-27 LH2 dump manifold pressurization Data review established the initiation-13 response (Concluded) of the helium flow into the manifoldwas delayed for 57 seconds. Once the

manifold repressurization heliumbegan flowing, the systemoperatednominally for the remainder of themission, providing helium for theduration of the post-MECO dump andduring entry. The failure had noimpact on the mission.Troubleshooting could not duplicateanomaly.Corrective Action:The MPSLH2manifoldrepressurization systemwill undergoadditional troubleshooting orregulator replacement duringturnaround operations at KSC.Closed. Criticality: Nominal 3/3;Abort 1.

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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAGE~-8-89 13NO. TITLE TIME COMMENTS MOO NO. RESP. MGR.

STS-27 Hydraulic system #2 accumulator low CAR 27RF06- When hydraulic system 2 main pump MMACS J. Grush-14 10 pressure switch was put to the -07 X39033CRIT lR2 "Normal" position during prelaunch S. McMillanoperations at 337: 14:24:48 G.m.t., X35913the bootstrap accumulator pressurelagged the main pump pressure byapproximately 15 seconds. Thebootstrap pressure theninstantaneously rose to equal themain pump pressure. No lag shouldhave occurred in the equalization ofthese pressures. Similarly, when thehydraulic system 2 main pumppressure was brought to "Normal"for entry at 341 :22 :52 :49 G.m.t., thebootstrap accumulator pressurelagged the main pump pressure byapproximately 5 minutes 25 secondsbefore rapidly equal iZint with themain pump pressure. In othinstances, when the bootstrapaccumulator pressure was equal tothe main pump pressure, bootstrapaccumulator pressure performanceremained nominal for the remainderof the auxiliary power unit operation.JSC Fcwm 318 (Feb 81) NASA-JSC


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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAGE~-8-89 14NO. TITLE TIME COMMENTS MOO NO. RESP. MGR.

5T5-27 Hydraulic d'stem #2 accumulator low Flight data indicated that the MMAC5 J. Grush-14 (Conclude ) hydraulic system 2 accumulator -07 X39033pressure and reservoir pressure S. McMillantracked each other in both instances X35913during the period before and afterthe lag~inl occurred, which impliesthat a c ec valve internal to thepriority valve was sluggish to open.The occurrence of this problem hadno impact on the mission.Corrective Action:The hydraulic system 2 priority valvewas removed and replaced. A failureanalysis will be performed and will betracked by CAR 27RF06 - 10 Closed.Crit ical ity 1R2.

.-5T5-27 Ku-band channel #2 ops rcdr dumps 340: 15:20 Ops rcdr dumps via KU-band ch 2 INCO J. Griffin-15 couldn't be recovered when KU in -05 X31449standby. With KU band on in comm D. Suitermode, ch 3 must be activated for X33339dumps to work on ch 2. Ch 3 thendeactivated, dumps still work on ch 2.Corrective Action:None. Ground procedure problem.Closed.JSCForm 318 (Feb 81) NASA-JSC


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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DA fE PA G E2-8-89 15NO. TITLE TIME COMMENTS MOD NO. RESP.MGR.

STS-27 PlBD ready -to -latch indicator hung up 337:15:59 During opening of starboard payload MMACS N. Jevas-16 CAR26RF04 bay door at approximately 337: 15: 59 -04 X38950CRIT3/3 G.m.t., the starboard forward ready- J.Gutheryto-latch indicator B (V37X3436Y) X33306remained on while indicators A and Cwent off asdesigned. Within a fewminutes, the B indicator alsowentoff. No further problems wereexperienced with the indicator forthe remainder of the mission. Testingat KSCcould not reproduce thefailure.Corrective Action:None. Switch module removed andreplaced. Closed. Criticality: Switchmodule 1R2; measurement 3 / 3 .CAR26RF04.

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PROBLEMTRACKING LIST STS-27IOV1 04 FINAL REPORT DATE PAGE1-23-89 16

NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.STS-27 TACAN # 1 prelaunch lock-on problem 337:09:42 During prelaunch navigation aids GNC-01 M. Schmalz-17 CRIT1R3 activation, at 9:34 G.m.t., TACAN 1 X30131was init ial ly powered up (MODE W. Leverichswitch to T /R ) with channel X30960thumbwheels set to 90X for the

blanking test. Approximately 2minutes later, the channelthumbwheels were set to 59Y toacquire the KSCground station.Automatic gain control (AGC)remained at 5.09 Vdc (indicating nosignal at the receiver), and range andbearing remained in the search mode.After approximately 6 minutes, theMODE switch was chcled to OFFthenback to T /R , at whic time AGC wentto approximately 3 Vdc (indicatingsignal at the receiver), and range andbearing locked on at 3.95 nmi. and268 degrees, respectively. Theseoperational conditions were not inviolation of Launch Commit Criteria(2 of 3 TACAN's required), and nofurther TACAN 1anomalies wereobserved for the remainder of theflight. Data analysis indicate allMODE switch and thumbwheel. contacts were good. Postflighttroubleshooting failed to reproducethe anomaly.Corrective Action:None, pendind recurrence of thefailure. Close . Critical ity lR3.

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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DATE PAGE~-O8-89 17NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.

STS-27 CFE/GFE: Crit: None Followin~ the humidity separator a) P.O.Smith-18 a) Volume Hdoor fasteners (CFE) anomaly reference problem 5T5-27- X38857OS),the crew opened the volume H D. Dillmandoor to clean up free water. After X31733door closure, four or five of the doorfasteners could not be re-engaged.The remainder of the fasteners weresuccessfully re-engaged. After theflight, the volume H door wasremoved and the fasteners andreceptacles were inspected. Noanomalies in the fasteners orreceptacles were noted. Followingthe inspection, the volume H doorwas re-closed and all of the fastenerssucessfullyengaged.Corrective Action:None, fly as is. Closed. Criticality:None.

5T5-27 b) Wet trash door & accesshatch After performing the free water b) F.-18 (CFE) cleanup in-flight maintenance McAllisterprocedures (reference problem 5TS- 3364427-05), the crew reported that thevolume Fwet trash accesspanelrequired more effort than normal toclose and that the volume Fwet trashdoor latch would not engage unless. the latch was pre-compressed duringclosure. The wet trash panel anddoor latch were retested at K5Candthe problems could not beduplicated. Corrective Action:None. Fly as is. Closed. Criticality:None.

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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT OAn PAGE2-8-89 18NO. TITLE TIME COMMENT;; MOO NO. RESP. MGR.

STS-27 c) Foot restraints on toilet (GFE) c) Foot rest on toilet difficult to c) H. Brasseaux-18 deploy and stow. Crew reported Jr. 339248evidence of gall ing.Corrective Action: At vendor forrework. Closed. Criticality: None.d) SPOC (carryon computer) (GFE) FIAR-BFC-022 d) One of the two Shuttle Portable d) L. McFadinFOOl Onboard Compuler (SPOC) units 38539onboard went to "Halt" anddisplayed the "Bad Pointer" faultmessage while executing the Centerof Gravity Manager software onflight day 4. The crew followedstandard procedures to reboot the

SPOCand the SPOCfunctionednormally during the remainder of themission.Corrective Action: None. Fly as is.Closed. Criticality: None.NASAJSCJSCForm 318 (Feb 81)


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PROBLEMTRACKING LIST STS-27/OV1 04 DATE PAGE~-8-89 19NO. TITLE TIME COMMENTS MOD NO. RESP.MGR.

STS-27 e) Galley water dispenser and FIAR BFCE- e) The crew reported that the galley e) F.McAliister-18 package- m-place lever problem. (GFE). 023-F001 dispensed approximately 25 percent 33644FIARBFCE- more water than the amount023-F002 selected. A similar report wasreceived from the 5T5-26 crew. In

addition, the "package-in-place"microswitch failed to diSenga~eapproximately 30 percent of t etimes after a package was removed.Testin~ of the packJe-in-Place leverafter t eflight faile to reproducethe microswitch problem.Corrective Action: For the nearterm, fly as-is. A detailed testobjective (OTO) is planned for 5T5-30(next OV-104 flight) to determinehow much extra water isdispensed.The OV-102 galley has beenrecalibrated to flow lesswater. If thepackage-in-place microswitchproblem is repeated, the problem canbe resolved by removing and re-inserting the package or by manuallymanipulating the microswitch.

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PROBLEM TRACKING LIST STS-27IOV1 04 FINAL REPORT DATE PAGE~-8-89 20NO. TITLE TIME COMMENTS MOO NO. RESP. MGR.

STS-27 e) Galley water dispenser & package in Analysis of the dispenser problem is e) F.Mcallister-18 place lever problem. (GFE). being tracked under FIAR BFCE-023- 33644(concluded) F001. Analysis of the package-in-placeswitch is being tracked under FIARBFCE-023-F002. Closed. Criticality:None

STS-27 Headset interface unit (HIU) anomaly FIAR-JSC-EE- During seat egress following the STS- M. Schmalz-19 0647 27 scrub, Mission Specialist 2(MS-2) x30131received a tin~le in the left ear while D. Suitertouching the eadset interface unit X33339(HIU) when other crewmembers weretalking. This problem was repeatedin the laboratory after the mission.The earphone-low signal wasinternally shorted to the metalfaceplate and when the MS-2touched the HIU, the circuit wascompleted to ground. When othercrewmembers spoke, a voltage waspresent on the earphone-low linewhich caused the problem. At athumbwheel setting of 5, the voltagepresent is 16 Vrms. At the maximumvolume control setting, the voltagepresent is 30 Vrms. At 30 Vrms thecircuit current is only 1-2 mao Whilethese levels of voltage and currentcan be felt, there is no electricalhazard for the crew.JSC Form 318 ( Feb 81) NASA-JSC


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PROBLEM TRACKING LIST STS-27/0V104 FINAL REPORT DA lE PAGE~-8-89 21

NO. TITLE TIME COMMENTS MOONO. RESP.MGR.ST5-27 Headset interface unit (HIU) anomaly FIAR-J5C-EE- Corrective Action: The transducer-19 (concluded) 0647 will be removed, replaced, andCrit 3R2 subjected to failure analysis. Theresults of this activity wil be tracked

by FIARJ5CEE647. A continuity testfor detecting shorts wil l beperformed on each unit prior toflight. Closed. Criticality: 3R2

STS-27 CCTV: FIARBF-CE- a) Closed circuit television (CCTV) B. Embry-20 a)TV monitor # 1would not display 029-F 003 monitor 1would not display video X30184video Crit lR3 from any signal source. The crew T. Welchfollowed malfunction procedures and X33335cycled power to monitor 1,and themonitor then worked properly for theremainder of the mission. Themonitor fault light came on whilesetting up for the secure CCTVdetailed test objective. There was novideo signal input to the monitor, butpower was applied. Under theseconditions, it isnormal for the faultlight to come on. This condition wasrepeated during postflight testing.

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PROBLEMTRACKING LIST STS-27/0V104 FINALREPORT DAlE PAGE2-8-89 22NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.

STS-27CCTV: FIARBF-CE- Corrective Action: The FI~ht Training B. Embry-20 a) TV monitor #1 (concluded) 029-F 003 Division has been notifie of the X]0184procedures to be used to prevent T. Welchrecurrence of this behavior. Tracked X33335by FIARBF-CE-029-F003. Closed.Criticality: IR3

CCTV: FIARBF-CE- b) The crew reported a thumping INCO-06 B. Embryb) Camera" A" 029-F005 noise when attempting to focus . X30184FIARBF-CE- camera A. The camera would not T. Welch029-F007 focus throughout the mission. X33335Crit 1R2 Postflight testing showed no problemin focusing the camera. Thethumping noise isan indicator ofproper performance of the camera.The malfunction hasbeendetermined to be in the monochromelens assembly rather than in thecamera.

5T5-27 CCTV: FIARBF-CE- Corrective Action: A FIARhasbeen INCO-06 B. Embry-20 b) Camera" A" (concluded) 029-F005 opened on the monochrome lens X30184FIARBF-CE- assembllc and will be returned to the T. Welch029-FOO7 vendor or failure analysis. Failure X33335analysis tracked by FIARBF-CE-029-F007. Closed. Criticality: 1R2c) Wrist camera FIARBF-CE- c)The remote manipulator system B. Embry029 F004 (RMS)wrist camera would not X30184Crit 1R2 respond to a gamma command. T. WelchPower was cycled and the camera X33335worked properly for the remainder ofthe mission. Postflight testing of thecamera showed normal operation.

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PROBLEMTRACKING LIST STS-21/0V104 F!NAL REPORT DATE PAGf2-8-89 23NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.

STS-27 c) Wrist camera FIARBF-CE- Corrective Action: The Crew Training B. Embry-20 (concluded) 029 F004 Division has been notified to advise X30184CRITlR2 subsequent crews of the procedures T. Welchto be used to prevent recurrence of X33 3 35this behavior. fAIR BFCE-029-F004.Closed. Criticality: 1R2.

STS-27 SPIrudder indicator biased CAR27RF11- The flight crew reported that during E.Dickinson-21 010 CRIT3 /3 entry, the surface position indicator X31117(SPJ)"OFF" flag was visible and the W. Leverichrudder position indicator appeared X30960stationary at approximately fourdegrees left. The flag isdriven byfault circuitry which detects adifference between commanded andactual indicator position. Postflighttroubleshooting at KSCfailed toreproduce the anomaly. The unit willbe removed and sent to the RockwellServicesCenter for additional testing.Disassembly of the unit isnot plannedunless a hard failure can be isolated.

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PROBLEMTRACKING LIST STS-27/0V104 FINALREPORT DATE PAGE2-8-89 24NO. TITLE TIME COMMENTS MOONO. R~SP.MGR.

STS-27 SPIrudder indicator biased Corrective Action: None,-21 (Concluded) pending hard failure. Closed.CAR27RF11; Criticality 3 /3

STS-27Temporary lossof OPS2 telemetry 337:14:51 Temporar~ lossof TLM from the OPS2 INCO-01 G. Salazar-22 RCDRtrac #2 during a playback X30162dump during ascent. RCDRat 29 W. Leverichpercent, no show of motion, and X20960percent tape not updating. Groundreceived dump modulation. Whenswitched to track 1, it operatedproperly. Continued operatingproperly throughout flight.Corrective Action: Closed, fly asis.

STS-27 MADS PCM 1 bite 340: 13:58 When the modular auxiliary data-23 CAR27RF15 system (MADS) was powered up atCRIT3 340: 13:58 G.m.t., a built-in testequipment (BITE)si~nal (V78X9611 E)was annunciated. T isSignal isgenerated by BITEcircuitry within theMADS Pulse Code Modulation (PCM)multiplexer unit. Power was cycled tothe MADS PCM and the BITEindication was reset. It did not recurfor the remainder of the mission. Thisanomaly had occurred previously onOV-104during checkout ofthe MADSPCMswitch on November 3, 1988, butcould not be reproduced insubsequent troubleshooting.

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PROBLEMTRACKING LIST STS-27/OV1 04 FINAL REPORT OAI~ PAGE~-8-89 25NO. TITLE TIME COMMENTS MOO NO. RESP.MGR.STS-27 MADS PCM 1 bite (Concluded) The decision was made at the time to INCO-04 G. Salazar-23 fly-as-is based on the criticality of the X30162system. During postflight W. Leverich

troubleshooting, the anomaly was X30960reproduced by increasing Main B busvoltage to 31Vdc. It was furtherisolated to within the MADS PCMmultiplexer unit. The unit wasremoved and replaced with the unitdesignated for OV-102.Corrective Action: The failed unit willbe returned to the vendor for failureanalysis by CAR 27RF15. ClosedCriticali ty: 3

STS-27 LH2 fill/drain valve response CAR27RFOS The main propulsion system (MPS) P Cota-24 CRITNominal liquid hydrogen (LH2) outboard fill X390373/3 Abort 1 /drain (PV11) closure times were 5 McMillangreater than allowed by specification X35913during prelaunch, MPSdump, and thefirst vacuum inerting. The valvefunctioned nominally for subsequentoperations during the second vacuuminerting and postflight trouble-shooting. The outboard fill/drainvalve closure response time ismeasured from the issuance of theclose command to the closedmicroswitch indication. Thespecification requires a maximumclosure time of 10seconds which wasexceeded during the followingmission events:

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PROBLEM TRACKING LIST STS-27 /OV1 04 FINAL REPORT 0"'1. P"'G~2-889 26NO. TITLE TIME COMMENTS MOO NO. RESP. MGR.

STS-27 LH2 fill/drain valve reponse Lift-off - 48 sec 10.876 sec-24 (Concluded) Propellant dump 13.276 secFirst vacuum inerting 12.776 secThe slow closure during the terminalcountdown sequencing came within0.12 second of causing a LaunchCommit Criteria (LCC) violation.Corrective Action:The actuator was removed andreplaced with an actuator thatexhibited rapid closure times undercryogenic condit ions duringacceptance tests. The removedactuator IS undergoing fai lureanalysis at the vendor and will betracked by CAR 27RFOS. An LCCchange IS being submitted to allow anadditional 3 seconds for valve closurebefore declaring a violation. CloseCriticality: Nominal 3.3 Abort 1.

2-8-89

David W. Camp. ManagerFlight Evaluation Office

JSCform 318(Feb81) NASAJSC

sts-27 national space transportation system mission report

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