1988 Space Shuttle Orbiter Systems Manual

8/21/2019 1988 Space Shuttle Orbiter Systems Manual

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2.1 AUXILIARY POWER UNIT/HYDRAULICS (APU/HYD)

CONTENTS

Description ........................................... 2.1-1

Fuel System.......................................... 2.1-2Gas Generator and Turbine................ 2.1-5Lubricating Oil..................................... 2.1-5Electronic Controller ........................... 2.1-6Injector Cooling System...................... 2.1-9APU Heaters ........................................ 2.1-11Water Spray Boilers............................. 2.1-12Main Hydraulic Pump........................ 2.1-17Hydraulic Reservoir............................ 2.1-20Hydraulic Accumulator...................... 2.1-20Circulation Pump and Heat

Exchanger...................................... 2.1-20Hydraulic Heaters ............................... 2.1-22Operations ............................................ 2.1-22

Auxiliary Power Unit

Description

The orbiter has three independent hydraulicsystems. Each consists of a main hydraulicpump, hydraulic reservoir, hydraulic bootstrapaccumulator, hydraulic filters, control valves,hydraulic/Freon heat exchanger, electricalcirculation pump, and electrical heaters.

Each system provides hydraulic pressure toposition hydraulic actuators for:

1. Thrust vector control of the mainengines by gimbaling the three SSMEs

2. Actuation of various control valves onthe SSMEs

3. Movement of the orbiter aerosurfaces(elevons, body flap, rudder/speed

brake)

4. Retraction of the external tank/orbiter17-inch liquid oxygen and liquidhydrogen disconnect umbilicals with-in the orbiter at external tank jettison

5. Main/nose landing gear deployment(system 1)/(system 1 or 2)

6. Main landing gear brakes and anti-skid

7. Nose wheel steering (system 1 withbackup from system 2).

Each hydraulic system is capable of operationwhen exposed to forces or conditions caused byacceleration, deceleration, normal gravity, zerogravity, hard vacuum, and temperaturesencountered during on-orbit dormant conditions.

Three identical, but independent, improved

auxiliary power units (APUs; also called IAPUs)provide power for the orbiter hydraulicsystems. The APU is a hydrazine-fueled,turbine-driven power unit that generatesmechanical shaft power to drive a hydraulicpump that produces pressure for the orbitershydraulic system. Each unit weighsapproximately 88 pounds and produces135 horsepower.

Each APU consists of a fuel tank, a fuel feedsystem, a system controller, an exhaust duct,lube oil cooling system, and fuel/lube oil vents

and drains. Redundant electrical heater systemsand insulation thermally control the systemabove 45 F to prevent fuel from freezing and tomaintain required lubricating oil viscosity.Insulation is used on components containinghydrazine, lube oil, or water to minimizeelectrical heater power requirements and tokeep high surface temperatures within safelimits on the turbine and exhaust ducts.


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The three APUs and fuel systems are located inthe aft fuselage. Each APU fuel system suppliesstorable liquid hydrazine fuel to its respectivefuel pump, gas generator valve module, and gasgenerator, which decomposes the fuel throughcatalytic action. The resultant hot gas drives a

single-stage, dual pass turbine. The turbineexhaust flow returns over the exterior of the gasgenerator, cooling it, and is then directedoverboard through an exhaust duct at the upperportion of the aft fuselage near the verticalstabilizer.

The turbine assembly provides mechanicalpower through a shaft to drive reduction gearsin the gearbox. The gearbox drives a fuel pump,a hydraulic pump, and a lube oil pump. Thehydraulic pump supplies pressure to thehydraulic system. The fuel pump increases the

fuel pressure at its outlet to sustain pressurizedfuel to the gas generator valve module and gasgenerator. The lube oil system supplieslubricant to the gearbox reduction gears anduses the reduction gears as scavenger pumps tosupply lube oil to the inlet of the lube oil pumpto increase the pressure of the lube oil system.

The lube oil of each APU is circulated through aheat exchanger in a corresponding water spray

boiler. Three water spray boilers (WSBs), onefor each APU, cool the lube oil systems. Thehydraulic fluid of each hydraulic pump driven

by an APU is also circulated through ahydraulic heat exchanger in the correspondingwater spray boiler to cool hydraulic fluid duringhydraulic system operation. The three WSBsare also located in the aft fuselage of the orbiter.

Fuel System

The APU fuel system (one for each of the threeAPUs) includes the fuel tank and fuel isolationvalves, the fuel pump, and fuel control valves.The improved APUs use passive heat sinks andheat shields to minimize the effects of heat

soakback.

Fuel Tanks

The APU fuel tanks are mounted on supportscantilevered from the sides of the internalportion of the aft fuselage. The fuel is storableliquid anhydrous hydrazine. The hydrazine isstored in a fuel tank with a total capacity of

about 350 pounds. The fuel tank, whichincorporates a diaphragm at its center, isserviced with fuel on one side and thepressurant (gaseous nitrogen) on the other. Thenitrogen is the force acting on the diaphragm(positive expulsion) to expel the fuel from the

tank to the fuel distribution lines and maintain apositive fuel supply to the APU throughout itsoperation. Each typical prelaunch fuel tankload is approximately 325 pounds. The fuelsupply supports the nominal power unitoperating time of 90 minutes in a mission or anydefined abort mode, such as an abort oncearound, when the APUs run continuously forapproximately 110 minutes. Under operatingload conditions, an APU consumes approxi-mately 3 to 3.5 pounds of fuel per minute

Auxiliary Power Unit Locations

The fuel tanks are 28-inch-diameter spheres.Fuel tanks 1 and 2 are located on the port side ofthe orbiters aft fuselage, and tank 3 is locatedon the starboard side. Each fuel tank is servicedthrough its respective fill and drain serviceconnections, located on the corresponding sideof the aft fuselage. The gaseous nitrogenservicing connection for each fuel tank is locatedon the same panel as the fuel servicingconnections on the corresponding side of the aftfuselage. The fuel tank is pressurized to 365 psi

prelaunch.

Each fuel tanks temperature and gaseousnitrogen pressure are monitored by the APUcontroller and transmitted to the GPC, wherequantity is calculated and transmitted to theAPU FUEL/H2O QTY meters on panel F8.When the switch below the meters on panel F8is positioned to FUEL, the quantity in APU fuel


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tanks 1, 2, and 3 is displayed simultaneously inpercent. The fuel quantity of 100 percent on themeter is equivalent to 350 pounds. Fuelpressure (psia) is shown on the FUEL PRESSmeter on panel F8. Fuel quantity in percent isalso displayed on the BFS SM SYS SUMM 2

display (FUEL QTY).

The gaseous nitrogen pressure in each fuel tankexerts a force on the tanks diaphragm to expelthe hydrazine fuel under pressure to the fueldistribution system. Filters are incorporatedinto each distribution line to remove anyparticles. The fuel distribution line branchesinto two parallel paths downstream of the filter.An isolation valve is installed in each parallelpath, providing redundant paths to permit fuelflow to the APU or to isolate fuel from the fuelsupply tanks.

APU Meters and Switches on Panel F8

Fuel pump seal cavitydrain catch bottle

Key:

- H2O

- N2H4

- Oil

APUcontroller

H2O

GN2

GN2

Injectorcooling

R

(3 )(rpm)

Gasgen

TurbineGearbox

Hydraulicmain pump

Oil pump

To waterspray boiler

From waterspray boiler

Overboard

Fuel control valves

Pri. Sec.

Fuel pump

Fuel testline

Pressurerelief valve

GN2

N2H4

Fueltank

Fuel tankvalves (2)

049.cvs

Improved APU Fuel System Schematic


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APU FUEL TK VLV Switches and Circuit Breakers on Panel R2

Fuel Tank Isolation Valves

Both isolation valves in each APU fueldistribution system are electrically poweredsolenoid valves, which are controlled by thecorresponding APU FUEL TK VLV 1, 2, 3switches on panel R2. They are energized openwhen the corresponding switch is positioned toOPEN; both valves are closed when the switch ispositioned to CLOSE, or if electrical power is

lost.

Each valve has a reverse relief function torelieve pressure on fuel trapped in the fueldistribution line downstream of the fuel tankvalves when both valves are closed. The valverelieves the downstream pressure when thepressure increases 40 psi to 200 psi above fueltank pressure due to heat soakback followingAPU shutdown.

The IAPU fuel tank isolation valves are cooledby fuel flow when the valves are open. Each

valve has redundant temperature measure-ments (two per valve, four per APU). Onetemperature reading for each valve is displayedon the BFS SM SYS SUMM 2 display and theAPU/HYD, DISP 86 display (Ops 201) besidethe FU TK VLV AT and BT labels. There aretwo tank isolation valve circuit breakers perAPU (one per valve) located on panel R2. Thesecan be pulled to disconnect electrical power

from the solenoid if a valve fails open or shorts.The valve heating profile, when the fuel isstagnant, is gradual and, in the event of a failedopen valve or short, permits adequate time forcorrective action.

Fuel Pump

Each APU fuel pump is a fixed-displacement,gear-type pump that discharges fuel at

approximately 1,400 psi to 1,500 psi andoperates at approximately 3,918 rpm. A fuelfilter is located at the fuel pump outlet, and arelief valve relieves at approximately 1,725 psi

back to the pump inlet if the filter becomesclogged.

Each fuel pump is driven by the turbine throughthe reduction gearbox. The fuel pumpreduction gear is located in the lube oil systemgearbox, and a shaft from the reduction geardrives the fuel pump. Seals are installed on theshaft to contain any leakage of fuel or lube oil.

If leakage occurs through the seals, it is directedto a drain line that runs to a 500-cubiccentimeter catch bottle for each APU. If thecatch bottle were overfilled, it would relieveoverboard at approximately 28 psia through adrain port. On ascent or entry, the flight crewcan monitor the catch bottles line pressure onthe BFS SM SYS SUMM 2 display (PMP LK P).


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0001/ /079 SM SYS SUMM 2 5 008/23:29:22

BFS 000/00:00:00

CRYO TK 1 2 3 4 5 MANF1 MANF2

H2 PRESS 208 208 206 206 206 208 207

O2 PRESS 816 815 814 814 814 815 815

HTR T1 -248 -248 -248 -248 -248

T2 -248 -248 -248 -248 -248

APU 1 2 3 HYD 1 2 3

TEMP EGT 942 942 942 PRESS 3064 3064 3064

B/U EGT 942 942 942 ACUM P 3080 3080 3080

OIL IN 250 250 250 RSVR T 116 153 142

OUT 264 264 264GG BED 511H 511H 511H QTY 72 74 71

INJ 1271 1271 1271

SPEED % 99 102 101 W/B

FUEL QTY 59 60 62 H2O QTY 78 73 78

PMP LK P 14 14 14 BYP VLV BYP BYP BYP

OIL OUT P 42 42 41

FU TK VLV

A T 63 65 62 THERM CNTL 1 28

B T 63 65 62 H2O PUMP P 23 63

AV BAY 1 2 3 FREON FLOW 2384 2384

TEMP 97 97 83 EVAP OUT T 38 38

A4 14 27.439 27.435 26.324 31.873 18.48

051

APU Information on BFS SM SYSSUMM 2 Display

Fuel Control Valves

The APUs operating speed is controlled by theprimary and secondary fuel control valves,which are installed in series downstream of thefuel pump. These are solenoid-operated pulser-type valves. In the normal APU operatingmode, the primary control valve pulses tomaintain the APUs speed at about 74,000 rpm(103%), while the secondary control valve ispowered fully open. If the APU is taken to highvia the APU SPEED SELECT switch on panelR2, the primary valve is unpowered and goes tofully open, while the secondary valve begins

pulsing, and controls APU speed at about 81,000rpm (113%). If the secondary valvesubsequently fails open, the primary valve will

begin pulsing to maintain APU speed at about83,000 rpm (115%) in the backup speed controlmode. If the secondary valve loses power, itgoes to the closed position and shuts down theAPU. As noted above, the primary valve goesto full open if it loses power, allowing thesecondary valve to take over automatically andcontrol at high speed (113%).

The crew can see APU speed on the BFS SM SYS

SUMM 2 display (APU SPEED %) in percent(100 percent = 72,000 rpm). The speedfluctuates due to the nature of the pulse-modulated fuel flow system.

For safety reasons, each APU has an automaticshutdown feature that will shut the APU downif the speed falls below 80 percent (57,600 rpm)or rises above 129 percent (92,880 rpm).

Gas Generator and Turbine

Each gas generator consists of a bed of Shell 405catalyst in a pressure chamber, mounted insidethe APU exhaust chamber. When the hydrazinefuel comes into contact with the catalyst, it

undergoes an exothermic reaction, decomposinginto a hot gas at approximately 1,700 F. Thegas expands rapidly and makes two passesthrough a single-stage turbine wheel, passesover the outside gas generator chamber andexits overboard through its own independentexhaust duct, located near the base of thevertical stabilizer. The temperature of the hotgas at the exhaust duct is approximately 1,000 F.

The shaft power from the spinning turbine issent to the hydraulic main pump associatedwith the APU via a speed reduction gearbox. It

is also used to drive the APUs fuel pump andlubrication oil pump.

The normal speed of the hydraulic main pump,APU fuel pump, and APU lube oil pump are3,918 rpm, 3,918 rpm, and 12,215 rpmrespectively. The lube oil system is necessary tolubricate the APU gearbox and the fuel pump.

The temperatures of the gas generator bed, thegas generator fuel injector, and the turbineexhaust gas are visible on the BFS SM SYSSUMM 2 CRT display (GG BED, INJ, TEMP

EGT). While the APU is running, the gasgenerator bed temperature transducer goes off-scale high at approximately 500 F. On orbit,when the APU is shut down, the gas generator

bed temperature transducer is useful formonitoring the bed temperature when the bed iskept warm by heaters.

Lubricating Oil

The APU lube oil system is a scavenger-typesystem with a fixed-displacement pump. EachAPU turbine through its gearbox drives a lube

oil pump at 12,215 rpm. The system ispressurized with gaseous nitrogen to provideadequate suction pressure to start the lube oilpump under zero-gravity conditions. Each lubeoil system has its own nitrogen gas storagevessel, which is pressurized to approximately140 psia. The pressurization system for eachlube oil system has a valve controlled by itscorresponding APU controller. The gaseous


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nitrogen pressurization valve for each powerunit is energized open by its correspondingcontroller when the gearbox pressure is below5.2 psi, plus or minus 1.3 psi, to ensure thatgearbox pressure is sufficiently above therequirements for proper scavenging and lube

pump operation.

The pump increases the lube oil pressure toapproximately 60 psi, directs the lube oil systemthrough the corresponding water spray boilerfor cooling, and returns the lube oil to theaccumulators and gearbox. The two accumula-tors in each lube oil system allow thermalexpansion of the lube oil, accommodate gasinitially trapped in the external lube circuit,maintain lube oil pressure at a minimum ofapproximately 15 psia, and act as a zero-gravity,all-altitude lube reservoir.

The following information is transmitted to theBFS SM SYS SUMM 2 display by the APUcontroller via the GPC: lube oil pump outletpressure (OIL OUT P) at approximately 45 psia,outlet temperature at approximately 270 F andreturn temperature from the water spray boiler(OIL IN, OUT) at approximately 250 F for eachAPU. The lube oil temperature of each APU isalso monitored on the APU OIL TEMP meter onpanel F8. The APU is selected by the switch

below the meter.

RDR ALTM

1

2

FLIGHT CNTLR PWR

ON

OFF

PSIA

100

80

60

40

20

0

100

80

60

40

20

0

% % % % FPSIA

X 10 00 X 10 00

4

3

2

1

0

4

3

2

1

0

100

80

60

40

20

0

100

80

60

40

20

0

FPSIA

X 100 X 100

14

12

10

8

6

4

2

0

4

3

2

1

0

5

1

2

3H O2

FUEL

FUEL

PRESSEGT

OIL

TEMP1 31 3 22 1 2 3

(LL)

FIREHOLE

PRESSURE QUANTITY FUEL / H2O QTYHYDRAULIC APU

APU OIL TEMP Meter and Switch on Panel F8(NOTE: EGT indicator on meter is driven by

TEMP EGT transducer seen on BFS SYSSUMM 2 CRT display.)

Electronic Controller

Each APU has its own digital controller. Thecontroller detects malfunctions, controls turbinespeed, gearbox pressurization, and fuelpump/gas generator heaters. Each controller is

controlled by its correspondingAPU CNTLR

PWR switch on panel R2. When the switch ispositioned to ON, 28-volt dc power is sent tothat controller and APU. The controllers areredundantly powered via dual internal remotepower controllers. When the switch is posi-tioned to OFF, electrical power is removed fromthat controller and APU.

APU Start

An APU/HYD READY TO START talkbackindicator for each APU is located on panel R2.

The talkback signals gray when that APUhydraulic system is ready to start; that is, whenthe APU gas generator temperature is above190 F, APU turbine speed is less than 80percent, WSB controller is ready, correspondingAPU fuel tank isolation valves are open, andcorresponding hydraulic main pump isdepressurized. When the APU is started, andits turbine speed is greater than 80 percent ofnormal speed, the corresponding indicatorshows barberpole.

NOTE

A barberpole APU/HYD READY TOSTARTtalkback will not inhibit a start.

APU OPERATE 1, 2, 3 switches are located onpanel R2. When the switches are positioned toSTART/RUN, the corresponding APU controlleractivates the start of that unit and removeselectrical power automatically from the unitsgas generator and fuel pump heaters.

To start the APU, fuel expelled from thehydrazine tank flows through the open tank

valves and filter to the gas generator valvemodule, which contains a primary andsecondary fuel control valve in series. Theprimary pulse control valve is normally open,and the secondary pulse control valve isenergized open. Fuel flowing through thepump bypass valve is directed to the gasgenerator, because the fuel pump is not beingdriven at that moment by the APU turbine.


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The fuel in the gas generator decomposesthrough catalytic reaction, creates hot gas, anddirects the hot gas to the single-stage turbine,which begins to rotate. The turbinesmechanical shaft drives the reduction gears,rotating the fuel pump, lube oil pump, and

hydraulic pump. The fuel pump increases thefuel pressure at its outlet and sustainspressurized fuel to the gas generator valvemodule and gas generator.

The startup logic delays the APU underspeedlogic check for 10.5 seconds after the startcommand is issued. This allows the APU toreach normal operating speed before theshutdown logic begins checking for a speedlower than 80 percent. The auto shutdowncapability of the controller can be disabled bytaking theAPU AUTO SHUT DOWNswitch on

panel R2 to INHIBIT.

The startup logic does not delay the APUoverspeed logic. If an overspeed is detected atany time by the controller, the F7 and MASTERALARM will annunciate. If the AUTO SHUTDOWN on panel R2 is ENABLED, the controllerwill automatically close the tank isolation valvesand close the secondary control valve.

CAUTION

After an APU auto shutdown, the APU

FUEL TK VLV switch must be taken toCLOSE prior to inhibiting auto shutdownlogic. Failure to do so can allow the fueltank isolation valves to reopen and flowfuel to an APU gas generator bed that isabove the temperature limits for saferestart.

APU Speed Control

When the APU turbine speed exceeds thecontrol target (103 percent for NORMAL and

113 percent for HIGH) the appropriate controlvalve closes. The fuel is then diverted through abypass line back to the fuel pump inlet. Whenthe turbine speed drops below the controltarget, the appropriate valve opens directingfuel to the gas generator and closing off the

bypass line. The primary fuel valve pulses tomaintain APU speed. The frequency andduration of the primary fuel control valve pulsesare functions of the hydraulic load on the unit.

The secondary fuel control valve normally staysfully open during the operation of the primary.If the primary valve loses power, it goes to thefully open position, and the secondary valve

begins pulsing and controlling APU speed. Ifthe secondary valve loses power at any time, the

APU is shut down. If the auxiliary power unit istaken to a high speed (by the APU SPEEDSELECTswitch on panel R2), the primary valveis unpowered and goes to the fully openposition while the secondary valve controls theunits speed.

Each APU controller controls the speed of eachunit upon the activation of the APU SPEEDSELECT switch for each APU on panel R2. TheNORM position controls the speed at 74,160rpm, 103 percent, plus or minus 8 percent. TheHIGHposition controls the speed at 81,360 rpm,

113 percent, plus or minus 8 percent, with asecond backup of 82,800 rpm, 115 percent, plusor minus 8 percent.

APU Auto Shutdown

The APU AUTO SHUT DOWN switches onpanel R2 enable the automatic shutdown featurein the associated APU controllers. When theswitch is positioned to ENABLE, each controllermonitors its corresponding APU speed. If thatAPU speed falls below 57,600 rpm (80 percent)or rises above 92,880 rpm (129 percent), the

controller automatically shuts down that unit.Each shutdown command closes that unitssecondary fuel valve and the tank isolationvalves.

Controller A or Benabled

Steam vent temperatureabove 130F

GN2shutoff valve open

Hydraulic bypass valvein proper position

Water Spray Boiler

Waterboilercontrollerready

APU fuel tankvalves open

Hydraulic main pumppressure normal

Readyto Start

Panel R2

APU controllerready signal

Gas generator temperature

above 190F

Turbine speed below 80%

APU Controller

053.cvs

APU Ready-for-Start Talkback Indicator Logic

When an APU AUTO SHUT DOWN switch ispositioned to INHIBIT, the automatic shutdownsequence for its APU controller is inhibited. Ifthe turbine speed falls below 80 percent or rises


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above 129 percent APU UNDERSPEEDor APUOVERSPEED caution and warning lights onpanel F7 will be illuminated, and a tone will begenerated, even though the APU AUTO SHUTDOWNswitch is in INHIBIT.

CAUTION

An APU should not be restarted after anoverspeed shutdown. Uncontained over-speed and turbine wheel breakup couldoccur if restart is attempted.

APU/HYD READY TO START Talkbacks, APU OPERATE Switches,APU SPEED SELECT Switches, APU CNTLR PWR Switches, and

APU AUTO SHUT DOWN Switches on Panel R2


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12

APUoverspeed

+

+APU 2

APU 3

Closes fueltank valves

055.cvs

APUunderspeed

C&WElectronics

PNL F7a2< 80%

ZE 65.2-2

PNL F7a2< 129%

APU 2

APU 3

Yellow

Yellow

Closes fueltank valves

CH2

CH4

UnderspeedDriver

ACH1

CH3

28VA

28VB

CH2

CH4

OverspeedDriver

BCH1

CH3

28VA

28VB

ZL 5C

O/S EXT 3C

O/S EXT 2C

O/S EXT 1A

O/S EXT 2A

O/S EXT 2B

O/S EXT 1B

O/S EXT 3B

O/S EXT 3A

CH2

CH4

S/OValveDriver

CH1

CH3

28VA

28VB

D

CH2

CH4

PCValveDriver

CH1

CH3

28VA

28VB

E

Primaryvalve

Secondaryvalve

ZE 65.2-2

APU Overspeed/Underspeed Detection

Injector Cooling System

The gas generator injector water cooling systemis used only when the normal cool-down periodof approximately 180 minutes is not available.The system sprays water to reduce thetemperature of the gas generator injector branchpassages to less than 400 F in the event that a

hot APU must be restarted after it has beenrecently shut down. The water cooling ensuresthat the hydrazine will not detonate in the fuelline leading into the injector due to heatsoakback from the gas generator. The injector iscooled by circulating water through it. Thewater from the gas generator injector isexhausted into the aft fuselage.


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1 3

ControlValves

GN2 H2O

APU3

APU2

APU1

Vlv open cmd

2

APU 1CONTROLLER

056.cvs

APU OPERATE

START/RUN

INJECTOR COOLPanel R2

APU Injector Cooling

A single water tank located in the aft fuselage ofthe orbiter serves all three APUs. The watertank is 9.4 inches in diameter and loaded with 9pounds (plus or minus 0.5 pound) of water. Thewater tank is pressurized with gaseous nitrogenat a nominal pressure of 120 psi. The pressureacts on a diaphragm to expel the water throughthree 0.25-inch-diameter lines to three controlvalves. When the APU OPERATE switch onpanel R2 for APU 1, 2, or 3 is positioned toINJECTOR COOL, the water valve of that unitopens and directs the water into the gasgenerator injector to cool it.

If the injector branch (internal) temperature ofan APU is above 400 F from heat soakback, orif the catalytic bed heater temperature is above430 F, the flight crew must cool the injector for3.5 minutes before starting the APU.Operational data from hot APUs shows that theGG INJ temperature does not accurately reflectthe drop in injector branch temperatures. The

crew is safe to attempt a restart if the GG INJtemperature is decreasing and at least 3.5minutes of continuous injector cooling has beencompleted. A Class 3 alarm with message "APU1 (2) Cooldown" will annunciate 225 seconds

after APU injector cooling is initiated

CAUTION

Care must be taken not to delay in the OFFposition when taking the APU OPERATEswitch to START/RUN. If cooldown isterminated more than 2 to 3 seconds priorto starting the APU, the injector branchtemperatures may increase above startlimits, and detonation may occur withoutanother cooldown cycle.

The water tank supply is sufficient for about sixhot starts, two per APU. The units injectortemperature can be monitored on the BFS SMSYS SUMM 2 display (INJ).

Fuel Pump and Gas GeneratorValve Module Cooling

The fuel pump and gas generator valve moduleare cooled by passive cooling. The improvedAPUs have passive heat sinks and heat shieldsto absorb conductive and radiant heat. This

prevents excessive heat soakback in the gasgenerator valve and fuel pump assemblies.There are no water tanks or associatedplumbing for this module with the APUs. Thecrew has no requirement to do anything toprovide cooling. This passive cooling system, inconjunction with active injector cooling, is usedto allow for contingency restarts in the event adeorbit becomes necessary within approxi-mately 180 minutes of APU shutdown.


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CAUTION

An APU may not be restarted if thetemperature of the fuel pump is above 210F or the temperature of the gas generatorvalve module is above 200 F, because

hydrazine detonation may occur.

APU Heaters

The APU HEATER TANK/FUEL LINE/H2OSYS 1A, lB, 2A, 2B, 3A, 3B switches on panelA12 operate the thermostatically controlledheaters located on the corresponding APU fuelsystem and water system. The fuel tank, fuelline, and water line heaters for each APU aredivided into redundant A and B systems foreach unit. For example, for APU 1, 1A and 1B,

the TANK/FUEL LINE/H2O SYS 1A switchcontrols the A heaters, and the thermostatsprovide automatic control. Only one set ofheaters is used at a time. The 1B switch controlsthe 1B heaters, and the thermostats provideautomatic control. The APU fuel tank and lineheater thermostats maintain the temperatures

between a nominal 55 F and 65 F. The watersystem heater thermostats maintain thetemperatures between 55 F and 65 F. The OFFposition of each switch removes power from therespective heater circuits.

The APU HEATER GAS GEN/FUEL PUMP 1,2, 3 switches on panel A12 operate thermostati-cally controlled heaters located on thecorresponding APU, fuel pump, and gasgenerator valve module, and provide power tothe gas generator bed heater. The thermostatscontrol a series of heaters on the gas generatorvalve module, fuel pump, and all the fuel lines

and the water lines from the fuel pump spraymanifold to the gas generator valve module.The heaters are divided into redundant A and Bsystems for each APU. The A AUTO switchcontrols the A heater, and the A thermostatautomatically controls the corresponding APU

fuel pump heater, maintaining fuel pump andgas generator valve module temperatures atabout 100 F. The gas generator bed heater ismaintained between 360 and 425 F by acompactor in the APU controller, which receivesits signal from the bed temperature transducer.The gas generator temperature range ensuresefficient APU startup through efficient catalyticreaction. The B AUTO switch position providesthe same capability for the B heater system. Thegas generator and fuel pump heaters areautomatically deactivated by the correspondingcontroller at APU start. The OFF position of

each switch removes power from the respectiveheater circuits. These heater switches alsoprovide redundant power to the gas generatorand gearbox pressure signal conditioners for usewhile the APU controller is off.

The lube oil system lines on each APU also havea heater system. These heaters are controlled bythe APU HEATER LUBE OIL LINE 1, 2, 3switches on panel A12. The lube oil line heatersfor each APU are also divided into an A and Bsystem: e.g., for 1, A AUTO and B AUTO. TheA AUTO switch controls the A heater, and the

thermostat automatically controls thecorresponding lube oil system heater,maintaining the lube oil line in the temperaturerange of 55 F to 65 F. The B AUTO switchposition provides the same capability to the Bheater system. The OFF position of each switchremoves power from the respective heatercircuits.


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APU HEATER Controls on Panel A12

Water Spray Boilers

The water spray boiler (WSB) system consists ofthree identical independent water spray boilers,one for each APU and hydraulic system. The

boilers are located in the aft fuselage of theorbiter. Each WSB cools the corresponding APUlube oil system and hydraulic system byspraying water onto their lines; as the water

boils off, the lube oil and hydraulic fluid arecooled. The steam that boils off in each water

spray boiler exits through its own exhaust duct,located on the starboard side of the verticalstabilizer.

Each WSB is 45 by 31 inches long by 19 incheswide, and including controller and vent nozzle,weighs 181 pounds. They are mounted in theorbiter aft fuselage between Xo1340 and 1400, atZo 488 minus 15, and at Yo plus 15. Insulation

blankets cover each boiler. The boiler's watercapacity is 142 pounds.

Each WSB stores water in a bellows-type storagetank pressurized by gaseous nitrogen providingpositive water expulsion to feed the boiler.Hydraulic fluid passes through the boiler threetimes. APU lube oil passes through the boilertwice. The hydraulic fluid tubes are sprayedwith water from three water spray bars, andtwo water spray bars spray the APU lube oil.Separate water feed valves allow independentcontrol of the hydraulic fluid spray bars andAPU lube oil spray bars. Redundant electrical

controllers provide completely automaticoperation.

The boiler system maintains APU lube oiltemperature at approximately 250 F and thehydraulic fluid in the range of 210 to 220 F.

The crew can see the WSB water quantity (H2OQTY), nitrogen tank pressure (N2 P), nitrogenregulator pressure (REG P), and nitrogen tanktemperature (N2 T) on the right side of the SMAPU/HYD (DISP 86) display on orbit.


13/663

Water Spray Boiler Unit

2011/ /086 APU/HYD 4 000/02:36:12

000/00:00:00

APU 1 2 3 HYD 1 2 3

B/U EGT 313 313 310 B/U P 64 64 64

EGT 313 313 310 RSVR T 58 64 66

SPEED % 0L 0L 0L P 65 66 66

FUEL QTY 76 77 77 QTY 74 75 73

TK P 209 210 212 ACCUM P 2616 2624 2624

OUT P 209 210 212

TK VLV A CL CL CL

A T 61 62 62

B CL CL CL

B T 61 62 62 W/B 1 2 3OIL T 64 63 62

OUT T 63 62 60 CNTLR A A A

OUT P 25 25 25 H2O QTY 100 100 100

GBX P 25 25 25 N2 P 2499 2506 2492

N2 P 141 142 140 T 57 58 55

BRG T 82 81 84 REG P 28 28 28

GG BED T 426 423 421 BYP VLV BYP BYP BYP

PUMP/VLV VENT T +122L +122L +122L

PMP T 94 92 90 TANK T + 57 + 58 + 55

VLV T 114 111 107 BLR T + 60 + 58 + 61

059

SM APU/HYD Display (DISP 86)


14/663

Gaseousnitrogenvent

Gaseous nitrogenregulator andrelief valve

Water fill

Gaseous nitrogenshutoff valve Gaseous

nitrogenfill

Steamduct

outlet

Steam ventdump nozzle

Vent heatersSteam vent

Hydraulicbypass/relief valve

Hydraulic fluidbypasses boilerwhen it decreasesto 190F. Hydraulicfluid directed throughwater boiler at 210F

Vent

Hydraulic fluid208F set-pointtemperatureturns onhydraulic-fluidwater feed valve

Lube oil

250F set-pointtemperature turnson APU lube oilwater feed valve

Water fill/drain

Lube oildrain

Boilerheaters

Water supplyvalve (hydraulic)

Water supplyvalve (lube)

Primarycontroller

Secondarycontroller

Gaseousnitrogen

tank

Tankheaters

Watertank

142 Poundswater

Gaseous

nitrogen PP

T

T

T(B )

(A)

T T

T T

060.cvs

Water Spray Boiler (One of Three)

Nitrogen Supply System

The gaseous nitrogen pressure for each WSB iscontained in a corresponding 6-inch sphericalpressure vessel. The pressure vessel contains0.77 pound of nitrogen at a nominal pressure of2,400 psi at 70 F. The gaseous nitrogen storagesystem of each WSB is directed to its corre-sponding water storage tank. Each storagevessel contains sufficient nitrogen gas to expelall the water from the tank and allow for reliefvalve venting during ascent.

The nitrogen shutoff valve between the pressurevalve and water storage tank of each boiler

permits the pressure to reach the nitrogenregulator and water tank or isolates the nitrogensupply from the water tank. Each nitrogenvalve is controlled by its respective BOILER N2SUPPLY 1, 2, or 3 switch on panel R2. Thenitrogen shutoff valve, which is latched open orclosed, consists of two independent solenoidcoils that permit valve control from either theprimary or secondary controller.

A single-stage regulator is installed between the

nitrogen pressure shutoff valve and the waterstorage tank. The gaseous nitrogen regulator foreach water spray boiler regulates the high-pressure nitrogen between 24.5 and 26 psig as itflows to the water storage tank.

A relief valve is incorporated inside eachnitrogen regulator to prevent the water storagetank pressure from exceeding 33 psig. Thegaseous nitrogen relief valve opens between 30to 33 psig.

Water Supply System

The water supply for each boiler is stored in apositive-displacement aluminum tank contain-ing a welded metal bellows separating thestored water inside the bellows from thenitrogen expulsion gas.


15/663

BOILER Switches on Panel R2

Redundant pressure and temperature sensorslocated downstream from the gaseous nitrogenpressure vessel and on the water tank for each

boiler transmit the pressures and temperaturesthrough each controller to the systems manage-ment general-purpose computer. The computercomputes the water tank quantity from thepressure, volume, and temperature, andtransmits the water tank quantity to panel F8 for

each boiler. The switch below the meter onpanel F8 is positioned toH

2Oto allow the water

quantity of each boiler to be displayed on theAPU FUEL/H2O QTY 1, 2, or 3 meter. Waterquantity is available when either the A or Bcontroller is powered.

Downstream of the water storage tank, thefeedwater lines to each water boiler split into

two parallel lines: one line goes to the hydraulicfluid flow section and one to the lube oil sectionof the WSB. The H2O spray valves in eachfeedline are controlled independently by the

boiler controller.

Temperature Control

The two boiler controllers are operated by the

respective BOILER CNTLR/HTR 1, 2, and 3switches on panel R2. When the applicableswitch is positioned to A, the A controller forthat boiler is powered; if it is positioned to B, theB controller is powered. The OFF positionremoves electrical power from both controllers.


16/663

APU FUEL/H2O QTY Meter and Switch on Panel F8

The BOILER PWR 1, 2, and 3switches on panelR2 enable (provide the automatic controlfunctions) the specific controller A or B selectedfor that boiler by the BOILER CNTLR/HTR 1, 2,

and 3 switches on panel R2. When the applica-ble controller A or B is enabled for that boiler, aready signal is transmitted to the correspondingAPU/HYD READY TO START indicator onpanel R2 if the following additional conditionsare met: gaseous nitrogen shutoff valve is open,steam vent nozzle temperature is greater than130 F, and hydraulic fluid bypass valve is in thecorrect position with regard to the hydraulicfluid temperature.

The core of each WSB is a stainless steelcrimped-tube bundle. The hydraulic fluid sec-tion is divided into three 17-inch-long passes ofsmooth tubes (first pass-234 tubes, second pass-224 tubes, and third pass-214 tubes). The lubeoil section of the APU comprises two passeswith 103 crimped tubes in its first pass and 81smooth tubes in the second pass. The tubes are0.0125 of an inch in diameter with a wallthickness of 0.010 of an inch. Crimps locatedevery 0.24 of an inch break up the internal

boundary layer and promote enhanced turbu-lent heat transfer. Although the second pass isprimarily a low-pressure drop return section,approximately 15 percent of the unit's lube oil

heat transfer occurs there. Three connectedspray bars feed the hydraulic fluid section,while two spray bars feed the power unit's lubeoil section in each boiler.

When the orbiter is in the vertical position onthe launch pad, each boiler is loaded with up to3.5 pounds of water, which is referred to as"pool mode" operation. When each APU/hydraulic system and WSB are in operation 5minutes before lift-off, the APU lube oil tube

bundle is immersed in the boiler waterprecharge. Liquid level sensors in each water

boiler prevent the water feed valves frompulsing to avoid water spillage or loss. As thevehicle ascends during launch, the lube oilsystem of the APU heats up, eventually the

boiler water precharge boils off, and the boilergoes into the spray mode about 8 minutes afterlaunch. The hydraulic fluid usually does notheat up enough during ascent to require spraycooling.


17/663

When the APU/hydraulic combination isstarted for atmospheric entry, the hydraulicfluid and power unit lube oil flow commences,fluid temperatures rise, and spraying is initiatedas required. During the lower part of entry,when the boiler temperature reaches 188 F, the

water spray boiler returns to the pool mode.The spray bars begin discharging excess waterto fill the boiler. When the water reaches theliquid level sensors, the spray is turned off sothat the boiler is not overfilled. During entry,

because the orbiter's orientation is differentfrom that of launch, the boiler can hold up to 14pounds of water.

The enabled controller of the operating WSBmonitors the hydraulic fluid and lube oil outlettemperature from the APU. The hydraulic fluidoutlet temperature controls the hydraulic fluid

H2O spray control valve, and the lube oil outlettemperature controls the lube oil water spraycontrol valve. Signals are based on a compari-son of the hydraulic system fluid temperature toits 208 F set point and of the lube oil of thepower unit to its 250 F set point. When therespective water feed valve opens, instantane-ous flows of 10 pounds per minute maximumthrough the hydraulic section and 5 pounds perminute maximum through the lube oil sectionenter the water boiler through the correspond-ing spray bars to begin evaporative cooling ofthe hydraulic fluid and APU lube oil. The steam

is vented out through the overboard steam vent.

The separate water feed valves modulate thewater flow to each section of the tube bundlecore in each WSB independently in 200-millisec-ond pulses that vary from one pulse every 10seconds to one pulse every 0.25 of a second.

Because of the unique hydraulic system fluidflows, control valves are located in the hydraulicsystem fluid line section of each WSB.Normally, hydraulic system fluid flows at up to21 gallons per minute; however, the hydraulic

system experiences 1- to 2-second flow spikes atup to 63 gallons per minute. If these spikeswere to pass through the boiler, pressure dropwould increase ninefold and the boiler wouldlimit the flow of the hydraulic system. Toprevent this, a relief function is provided by aspring- loaded poppet valve that opens whenthe hydraulic fluid pressure drop exceeds 48 psiand is capable of flowing 43 gallons per minute

at a differential pressure of 50 psi across theboiler. A temperature controller bypass valveallows the hydraulic fluid to bypass the boilerwhen the fluid temperature decreases to 190 F.At 210 F, the controller commands the bypassvalve to direct the fluid through the boiler.

When the hydraulic fluid cools to 190 F, thecontroller again commands the valve to routethe fluid around the boiler. Bypass valve (BYPVLV) status is available on the followingdisplays: SM SYS SUMM 2 (PASS AND BFS)and PASS DISP 86 APU/HYD.

Heaters

Each water boiler, water tank, and steam vent isequipped with electrical heaters to preventfreeze-up in orbit. The water tank and boilerelectrical heaters are activated by the corre-

sponding BOILER CNTLR/HTR 1, 2, and 3switches on panel R2. The A or B position ofeach switch selects the A or B heater system andis automatically controlled by the correspondingA or B controller. The steam vent heaters arealso activated by the BOILER CNTLR/HTR 1, 2and 3switches but only if the BOILER PWR 1,2or 3switch on panel R2 is ON. The water tankand boiler heaters are cycled on at 50 F and offat 55 F. The steam vent heaters are not oper-ated continuously in orbit; they are activatedapproximately two hours before APU startup.The steam vent heaters are cycled on at 150 F

and cycled off at 175 F.

Main Hydraulic Pump

The main hydraulic pump for each hydraulicsystem is a variable displacement type. Eachoperates at approximately 3,900 rpm whendriven by the corresponding APU.

Each main hydraulic pump has an electricallyoperated depressurization valve. The depres-surization valve for each pump is controlled byits corresponding HYD MAIN PUMP PRESS 1,

2, or 3 switch on panel R2. When the switch ispositioned to LOW, the depressurization valveis energized to reduce the main hydraulic pumpdischarge pressure from its nominal range of2,900 to 3,100 psi output to a nominal range of500 to 1,000 psi to reduce the APU torquerequirements during the start of the APU. "APUPress Low" is one of the inputs required to get agray READY TO START talkback.


18/663

NOTE

An APU cannot be successfully startedwith HYD MAIN PUMP PRESS posi-tioned to NORM.

After an APU has been started, thecorresponding HYD MAIN PUMP PRESSswitch is positioned from LOWto NORM. Thisde-energizes the respective depressurizationvalve, allowing that hydraulic pump to increaseits outlet pressure from 500 to 1,000 psi to 2,900to 3,100 psi. Each hydraulic pump is a variabledisplacement type that provides 0 to 63 gallonsper minute at 3,000 psi nominal with the APU atnormal speed and 69.6 gallons per minute at3,000 psi nominal with the APU at high speed.

Main pump outlet pressure (HYD PRESS) can

be seen by the crew on the BFS SM SYS SUMM

2 or PASS DISP 86 APU/HYD displays. A high-pressure relief valve in the filter module foreach hydraulic system also relieves the hydrau-lic pump supply line pressure into the returnline in the event the supply line pressureexceeds 3,850 psid.

A separate pressure sensor (sensor A) in thefilter module for each hydraulic systemmonitors the hydraulic system source pressureand displays the pressure on the HYDRAULICPRESSURE 1, 2, and 3 meters on panel F8. Thishydraulic pressure sensor also provides aninput to the yellow HYD PRESS caution andwarning light on panel F7 if the hydraulicpressure of system 1, 2, or 3 is below 2,400 psi.

HYD MAIN PUMP PRESS 1, 2, 3 Switches on Panel R2


19/663

T

Freon/hydheat exch

Thermalcontrol

valve

GN2

Accumulator

Watersprayboiler

T

WSB

cntlr

M

Hydraulicmain pump

Reservoir

M

Circulationpump

350psig

0p 2500 PSIGCl

PUnloadervalve

Open. P>2563 psigClose. P psigReseat P 2600< psig

P Priorityvalve

(relievesat 3000psid)

Hyd bypassvalve

Pressure

Return

Pressure

Return

NOTE: The system is shown in normal operation- APU on- Circ pump off

3000

psig

064.cvs

APU

Hydraulic System (Control Section)

HYDRAULIC PRESSURE and QUANTITY Meters on Panel F8(Driven by different sensor than CRT)


20/663

Hydraulic Reservoir

Hydraulic reservoir pressure is maintainedusing an accumulator bootstrap mechanism.The bootstrap uses a variable area pistonassembly to convert high pressure to the

accumulator to lower pressure in the reservoir(roughly 40:1). This reservoir pressuremaintains adequate hydraulic inlet pressure at

both the main pump and circulation pump toprevent cavitation during startup and operation.When the main hydraulic pump is in operation,the high-pressure side of the piston and the

bootstrap accumulator are pressurized to 3,000psig from the main pump discharge line. Whenthe main hydraulic pump is shut down, thepriority valve closes, and the bootstrapaccumulator maintains a pressure ofapproximately 2,500 psi. The 2,500 psi on the

high side results in a main pump inlet (low side)pressure of approximately 62 psia. Theminimum inlet pressure to assure a reliablemain pump start is 20 psia (which correspondsto a high-pressure side of 800 psi). This pre-vents the main pump from cavitating (notdrawing hydraulic fluid), which could damagethe pump.

The quantity in each reservoir is 8 gallons. Thehydraulic fluid specification is MIL-H-83282,which is a synthetic hydrocarbon (to reduce firehazards). The reservoir provides for volumetric

expansion and contraction. The quantity of eachreservoir is monitored in percent on theHYDRAULIC QUANTITY meters on panel F8.A pressure relief valve in each reservoir protectsthe reservoir from overpressurization andrelieves at 120 psid.

Hydraulic Accumulator

The accumulator is a piston type prechargedwith gaseous nitrogen at 1,650 to 1,750 psi. Thegaseous nitrogen capacity of each accumulator

is 96 cubic inches, and the hydraulic volume is51 cubic inches.

Circulation Pump and Heat Exchanger

The circulation pump is actually two fixed-displacement gear-type pumps in tandem,driven by a single motor. One is a high pres-sure, low-volume pump (2,500 psig), which is

used to maintain accumulator pressure whilethe hydraulic system is inactive in orbit. Theother is a low pressure, high-volume pump (350psig), which is used to circulate hydraulic fluidthrough the orbiter hydraulic lines while thehydraulic system is inactive in orbit in order towarm up cold spots. The hydraulic fluid iscirculated through a Freon/hydraulic fluid heatexchanger to pick up heat from the orbiter Freoncoolant loops. A temperature-controlled bypassvalve directs the hydraulic fluid through theheat exchanger if the temperature at the heatexchanger inlet is less than 105 F. The bypass

valve bypasses the fluid around the heatexchanger if the temperature is greater than 115 F.

An unloader valve at the circulation pumpoutlet directs the high pressure output from thecirculation pump into the accumulator until theaccumulator pressure is greater than 2,563 psia,then redirects the high pressure output tocombine with the low pressure output to thehydraulic lines.

0001/ /079 SM SYS SUMM 2 5 008/23:29:22

BFS 000/00:00:00


H2 PRESS 208 208 206 206 206 208 207

O2 PRESS 816 815 814 814 814 815 815HTR T1 -248 -248 -248 -248 -248

T2 -248 -248 -248 -248 -248

APU 1 2 3 HYD 1 2 3

TEMP EGT 942 942 942 PRESS 3064 3064 3064

B/U EGT 942 942 942 ACUM P 3080 3080 3080

OIL IN 250 250 250 RSVR T 116 153 142

OUT 264 264 264

GG BED 511H 511H 511H QTY 72 74 71

INJ 1271 1271 1271

SPEED % 99 102 101 W/B

FUEL QTY 59 60 62 H2O QTY 78 73 78


OIL OUT P 42 42 41

FU TK VLV

A T 63 65 62 THERM CNTL 1 28

B T 63 65 62 H2O PUMP P 23 63



A4 14 27.439 27.435 26.324 31.873 18.48

051

BFS SM SUMM 2 Display(Hydraulic System Values)


21/663

HYD CIRC PUMP Switches on Panel R2

Each circulation pump can be manually turnedon or off with the corresponding HYD CIRCPUMP switch on panel R2. If the switch isplaced in GPC, the pump will be activated anddeactivated by the SM GPC according to acontrol software program based on certainhydraulic line temperatures and/or accumula-

tor pressure. This program activates theappropriate circulation pump when any of thecontrol temperatures drop below either 0 F, or -10 F, depending on their locations, anddeactivates the circulation pump when all of thecontrol temperatures for that system are greaterthan 20 F, or after 15 minutes for system 1 and10 minutes for systems 2 and 3. Theactivation/deactivation limits for these controltemperatures can be changed during the flight

by crew or Mission Control.

The program also includes a timer to limit the

maximum time a circulation pump will run, anda priority system to assure that only onecirculation pump is on at a time (because ofexcessive power usage if more than onecirculation pump is on). Each circulation pumpuses 2 kW of electrical power. This softwarewill also automatically provide for the

repressurization of the hydraulic accumulatorwhen the pressure lowers to a value of 1,960 psi.In this contingency, the circulation pump willfirst receive the highest priority to operate andwill be turned ON while other circulationpumps are operating in thermal mode (thismeans that two pumps can be operating

simultaneously). After the pump has beenrepressurized, the accumulator above 1,960 psi,or a period of 2 minutes (this value can bechanged by Mission Control Center uplink) haselapsed, the circulation pump will be com-manded to OFF. It is possible to run all threecirculation pumps at the same time torepressurize accumulators.

The circulation pump is automatically discon-nected when its corresponding APU Runcommand is issued by the APU controller. Eachcirculation pump can be powered by one of two

orbiter main electrical buses, selectable by theHYD CIRC PUMP POWERswitches on panel A12.

The crew can see circulation pump outletpressure as well as the hydraulic line andcomponent temperatures on the PASS SM HYDTHERMAL display, DISP 87.


22/663

Hydraulic System Controls on Panel A12

2011/ /087 HYD THERMAL 4 000/02:36:29

000/00:00:00

CIRC PUMP CONTROL

HYD 1 2 3 LINE TEMPS 1 2 3

CIRC PMP P 64 66 66 ELEVON LOB+ 94 + 61 + 59


PMP BDY T+ 61 + 47 + 47 LIB+ 94 + 61 + 61

RSVR T+ 58 + 64 + 66 RIB+ 94 + 61 + 61

ACCUM P2616 2624 2624 ROB+ 94 + 59 + 61

HX IN T+ 75 + 75 + 75 RD/SB PDU+ 97 + 59 + 59

OUT T+ 59 + 54 + 54 FUS+ 97 + 59 + 59

BDYFLP PDU+ 97 + 59 + 59SW VLV PR S1 S2 FUS+ 97 + 59 + 59

ELEV L OB 3* 1 2 L BRAKE WHL + 70 + 45

IB 2* 1 3 FUS + 70 + 45

R IB 3* 1 2 R BRAKE WHL+ 62 + 70 + 61

OB 2* 1 3 FUS+ 40 + 67 + 61

RUD/SPDBK 1* 2 3 NG UPLK+ 40

MFUS 1+ 40

TIRE PRESS MFUS 2+ 40

MG LEFT RIGHT MG L UPLK+ 40

IB 377 377 377 377 MG R UPLK+ 40

OB 378 378 376 376 FUS+ 40

NG 369 369 364 364

068

SM HYD THERMAL Display (DISP 87)

The SM APU/HYD display (DISP 86) shows thehydraulic system pressure, reservoir tempera-ture, reservoir quantity (in percent), andhydraulic accumulator pressure.

Hydraulic Heaters

Areas of the hydraulic lines that cannot bewarmed by fluid circulation while the system isinactive on-orbit are warmed by heaters. Theseheaters are automatically controlled by thermo-stats to maintain the hydraulic line temperaturesin a specified range. Each heated area hasredundant heaters (A and B), which are con-trolled by the HYDRAULIC HEATER switcheson panel A12.

Operations

The WSB controllers are powered up at launchminus 8 hours, and the boiler water tanks arepressurized in preparation for APU activation.The controllers activate heaters on the watertank, boiler, and steam vent to assure that thewater spray boiler is ready to operate for launch.

APU start is delayed as long as possible to savefuel. At T minus 6 minutes 15 seconds, the pilot

begins the prestart sequence. The pilot confirmsthat the WSB is activated, then activates theAPU controllers and depressurizes the mainhydraulic pump. Depressurizing the mainpump reduces the starting torque on the APU.The pilot then opens the fuel tank valves andlooks for three APU ready-to-start indications(gray talkbacks). At T minus 5 minutes, thepilot starts the three units by setting the APUOPERATE switches to START/RUN and checksthe hydraulic pressure gauges for an indicationof approximately 800 psi. Then the pilotpressurizes the main pump and looks forapproximately 3,000 psi on the gauges. All threehydraulic main pump pressures must be greaterthan 2,800 psi by T minus 4 minutes, or the

automatic launch sequencer will abort the launch.

The APUs operate during the ascent phase andcontinue to operate through the first OMS burn.At the conclusion of the main engine purge,dump, and stow sequence, the APUs and WSBsare shut down. The same sequence applies for adelayed OMS-1 burn. If an abort once around isdeclared, the APUs are left running, but thehydraulic pumps are depressurized to reducefuel consumption. The units are left running toavoid having to restart hot APUs for deorbitand re-entry.

Six hours after lift-off, or as soon as they arerequired, depending on the environment, thegas generator/fuel pump heaters are activatedand are in operation for the remainder of theorbital mission. The fuel and water line heatersare activated immediately after APU/HYDSHUTDN in the post OMS-1 timeframe to preventthe lines from freezing as the APUs cool down.


23/663


24/663

APU/HYD Caution and Warning Summary

The yellowAPU TEMPcaution and warninglight on panel F7 is illuminated if the APU 1,2, or 3 lube oil temperature is above 290 F.

The yellow APU OVERSPEED light isilluminated if APU 1, 2, or 3 turbine speed ismore than 92,880 rpm (129%). If the APUAUTO SHUT DOWNswitch on panel R2 is inENABLE, an automatic shutdown of thatAPU will occur.

The yellow APU UNDERSPEED light isilluminated if APU 1, 2, or 3 turbine speed isless than 57,600 rpm (80%). If the APUAUTO SHUT DOWNswitch for that APU isin ENABLE, an automatic shutdown will

occur.

Placing theAPU AUTO SHUT DOWNswitchin INHIBIT only inhibits the automaticshutdown of that APU if its turbine speed isless than 80% or more than 129%. The APUUNDERSPEED or APU OVERSPEED lightwill always illuminate, and a tone will be

generated.

The yellow HYD PRESS light illuminateswhen hydraulic system 1, 2, or 3 drops below2,400 psi for any reason.

The blue SM ALERT illuminates, and theC/W tone is sounded if turbine speed falls

below 80% or rises above 129%.

The red BACKUP C/W ALARM illuminates ifhydraulic pressure of system 1, 2, or 3 drops

below 2,400 psi.

O2PRESS H2PRESSFUEL CELL

REACFUEL CELL

STACK TEMPFUEL CELL

PUMP

CABIN ATMO2HEATER

TEMP

MAIN BUSUNDERVOLT

ACVOLTAGE

ACOVERLOAD

FREONLOOP

AV BAY/CABIN AIR

IMU FWD RCS RCS JET

H2O LOOP RGA/ACCEL AIR DATA LEFT RCS RIGHT RCS

LEFT RHC RIGHT/AFT

RHC

LEFT OMS RIGHT OMS

PAYLOADWARNING

GPCFCS

SATURATIONOMS KIT OMS TVC

PAYLOADCAUTION

PRIMARY C/WFCS

CHANNELMPS

(R)

(R)

(R)

(R)

(R)

(R)

(R)

BACKUP C/WALARM

APUOVERSPEED

APUUNDERSPEED

HYD PRESSAPU

TEMP

070

(R)

(R)

(R)

(R)

(R)

APU/HYD Caution and Warning Lights on Panel F7


25/663


26/663

TB gray indicates:

GGT > 190FAPU speed < 80%Fu tk vlvs - OPHyd mn pump P - LowWb ok when:

Cntrl A(B) - ENAVent T > 130FGN2 vlv - OPHyd byp vlv - BYP

Control powerAuto shut down

Speed selectOper start

Rdy tostart TB

Inj cooling

AP Ucontrol AP Uoverspeeed

AP Uunderspeed

Fuel pump(2 inparallel)

(COMP)Q

GEAR BOX I/F WITH FUEL PUMP OIL PUMP HYD PUMP

AP Ufueltank

valves

N2H4

GN2

T

T

T

P

GN2

X X

XX

X X

XX

XX

X

X

XX

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X X XX

X

X

X

X

X

X

X

X

X

XX

X X

T

P

P

X

P

X

Priority valvecloses at 2600 psia

X

P

Hyd press

Circpump

X40 0psia

X

2500psia

X

X

X

Freonhx

X

X

X

X

X

XX

XX X X X

X

X

X

X

X

X

X

X

X

XXXXXXX

X X X

X

XX

Byp vlv< 190F

Isolvlvs

SSMEET umb

X

X

X

XXX

XX

X

X

X

X

X

X

X

X

X

X

X

WB on at> 250F

X

(Comp)

X

Q

X

H2O

X

X

X X

X

X

X

X

X

X

X

X

P

X

T

X

X

X X

Reservoir

X X

GN2

T

P

Q

X Z

WBcntlr

Z

Boiler N2 supply

Z

Boiler cntlr/htr

Z

Z

Z

Boiler powerAPU temp

Exhaust

Z

Z

Z

T T

T

Z

L

X

L

X

L

X

XX

L

L

L

X

X

X

L

L

L

X

X

L

L

X

X

L

L

X

X

L

L

X

X

LL

X

X

L

L

X

L

X

LX

L

X

L

X

L

X

L

L

L

L

L

L

L

L

L L L L L L L L L LL

L L L L L L L L L LL

L

L

Bypassvalve> 105F

Oil pump

P T

P

Gas gen TurbineGN2H20

Gear box

(RPM)

Hyd main pump3000psia

T T P R

P

Vent

T

TT

Brakes

Lg

nws

(Sys 1)

only

Elevrudderspd brk

bdy flp

071.cvs

APU/Hydraulic Overview


27/663

Panel R2


28/663

Panel F8


29/663

Panel A12


30/663

0001/ /079 SM SYS SUMM 2 5 008/23:29:22

BFS 000/00:00:00


H2 PRESS 208 208 206 206 206 208 207

O2 PRESS 816 815 814 814 814 815 815

HTR T1 -248 -248 -248 -248 -248

T2 -248 -248 -248 -248 -248

APU 1 2 3 HYD 1 2 3

TEMP EGT 942 942 942 PRESS 3064 3064 3064

B/U EGT 942 942 942 ACUM P 3080 3080 3080

OIL IN 250 250 250 RSVR T 116 153 142

OUT 264 264 264

GG BED 511H 511H 511H QTY 72 74 71

INJ 1271 1271 1271

SPEED % 99 102 101 W/B

FUEL QTY 59 60 62 H2O QTY 78 73 78


OIL OUT P 42 42 41

FU TK VLV

A T 63 65 62 THERM CNTL 1 28

B T 63 65 62 H2O PUMP P 23 63



A4 14 27.439 27.435 26.324 31.873 18.48

051

DISP 79 SM SYS SUMM 2 Display(PASS and BFS)

2011/ /086 APU/HYD 4 000/02:36:12

000/00:00:00

APU 1 2 3 HYD 1 2 3

B/U EGT 313 313 310 B/U P 64 64 64

EGT 313 313 310 RSVR T 58 64 66

SPEED % 0L 0L 0L P 65 66 66

FUEL QTY 76 77 77 QTY 74 75 73

TK P 209 210 212 ACCUM P 2616 2624 2624

OUT P 209 210 212

TK VLV A CL CL CL

A T 61 62 62

B CL CL CL

B T 61 62 62 W/B 1 2 3

OIL T 64 63 62

OUT T 63 62 60 CNTLR A A A

OUT P 25 25 25 H2O QTY 100 100 100

GBX P 25 25 25 N2 P 2499 2506 2492

N2 P 141 142 140 T 57 58 55

BRG T 82 81 84 REG P 28 28 28

GG BED T 426 423 421 BYP VLV BYP BYP BYP

PUMP/VLV VENT T +122L +122L +122L

PMP T 94 92 90 TANK T + 57 + 58 + 55

VLV T 114 111 107 BLR T + 60 + 58 + 61

SM APU/HYD Display (PASS DISP 86)

2011/ /087 HYD THERMAL 4 000/02:36:29

000/00:00:00

CIRC PUMP CONTROL

HYD 1 2 3 LINE TEMPS 1 2 3



PMP BDY T+ 61 + 47 + 47 LIB+ 94 + 61 + 61

RSVR T+ 58 + 64 + 66 RIB+ 94 + 61 + 61

ACCUM P2616 2624 2624 ROB+ 94 + 59 + 61

HX IN T+ 75 + 75 + 75 RD/SB PDU+ 97 + 59 + 59

OUT T+ 59 + 54 + 54 FUS+ 97 + 59 + 59 BDYFLP PDU+ 97 + 59 + 59

SW VLV PR S1 S2 FUS+ 97 + 59 + 59

ELEV L OB 3* 1 2 L BRAKE WHL + 70 + 45

IB 2* 1 3 FUS + 70 + 45

R IB 3* 1 2 R BRAKE WHL+ 62 + 70 + 61

OB 2* 1 3 FUS+ 40 + 67 + 61

RUD/SPDBK 1* 2 3 NG UPLK+ 40

MFUS 1+ 40

TIRE PRESS MFUS 2+ 40

MG LEFT RIGHT MG L UPLK+ 40

IB 377 377 377 377 MG R UPLK+ 40

OB 378 378 376 376 FUS+ 40

NG 369 369 364 364

068

SM HYD THERMAL Display (PASS DISP 87)

2011/ /088 APU/ENVIRON THERM 4 000/02:36:51

FREON LOOP 1 2 000/00:00:00

ACCUM QTY 27 27 H2O LOOP 1 2

FREON FLOW 2193 2190 PUMP OUT P 64 62

PL HX FLOW 290 286 OUT T 64 63

AFT CP FLOW 279 278 P 3OL 38

RAD IN T 97 96 ICH FLOW 564L 777

RAD OUT T 38 38 OUT T 41 38

EVAP OUT T 38 38 CAB HX IN T 42 38

EVAP TEMP DUCT NOZ ACCUM QTY 45 55

HI LOAD INBD 259 APU FUEL T 1 2 3

OUTBD 259 312 TK SURF + 69 + 67 + 68

TOPPING FWD 257 TK HTR + 70 + 68 + 69

AFT 257 TEST LN 1 + 62 + 62 + 63

L 162 50 TEST LN 2 + 62 + 63 + 63

R 162 50 FEED LN + 57 + 58 + 58

EVAP FDLN T A B PUMP IN + 57 + 58 + 58

FWD 80 80 DRN LN 1 + 62 + 62 + 63

MID 1 80 80 DRN LN 2 + 62 + 62 + 63

MID 2 79 75 OUT + 92 + 90 + 88

AFT 75 79 BYP LN +108 +106 +102

TOPPING 75 79 GG SPLY LN 113 111 107

ACCUM 75 79

HI LOAD 75 79 H2O LN INJ+ 71 92 + 72

078

APU/ENVIRON THERM (PASS DISP 88)


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2.2 CAUTION AND WARNINGSYSTEM (C/W)

CONTENTS

Description ........................................... 2.2-1

Alarms................................................... 2.2-2

Smoke Detection and FireSuppression................................... 2.2-5

Rapid Cabin Depressurization .......... 2.2-10

Operations ............................................ 2.2-11

SPEC 60, SM Table Maintenance....... 2.2-14

F7 Light Summary............................... 2.2-19

Fault Message Summary .................... 2.2-22

DescriptionThe caution and warning system warns thecrew of conditions that may create a hazardto orbiter operation and/or crew. Under certaincircumstances, the system also alerts the crewto situations that require time-critical (under 5minutes) procedures to correct them. Thesystem uses data such as temperature, pres-sure, flow rates, and switch positions todetermine whether an alarm situation exists.

The system consists of software and electronicsthat provide the crew with visual and aural cueswhen a system exceeds predefined operatinglimits. Visual cues consist of four red MASTERALARM lights, a 40-light array on panel F7, a120-light array on panel R13U, and CRT

messages. The aural cue is sent to thecommunications system for distribution to flightcrew headsets or speaker boxes.

The crew interfaces with the C/W systemthrough panel R13U, panel C3, CRT displays,panel F7, panel L1, and the four red MASTERALARM pushbutton indicators on panels F2, F4,A7, and MO52J.

The C/W system interfaces with the auxiliarypower units, data processing system, environ-mental control and life support system,electrical power system, flight control system,

guidance and navigation, hydraulics, mainpropulsion system, reaction control system,orbital maneuvering system, and payloads.

Inputs enter the software C/W logic circuitryfrom the onboard computers through multi-plexers/demultiplexers (MDMs) to activatealarm tones and the BACKUP C/W ALARM.Some of these are used to turn on the BACKUPC/W ALARM light on panel F7 while crewinput resets the MASTER ALARM lights and tones.

Hardware Only

Siren KlaxonMA l ights MA lightsSmokedetectionlights

Hardware

C&W toneMA lightsF7 lightsR13 lights

Software

C&W toneMA lightsF7 B/U lightFault msg

EmergencyClass 1

Caution & Warningclass 2

AlertClass 3

AlarmAnnunciation

FireSmoke

-dP/dTPrimaryC&W

BackupC&W

Software

Alert toneSM light

Fault message

Software

Status parameters

Limit SensingClass D

079.cvs

Caution and Warning Diagram


32/663

Alarms

Four alarm classes constitute the C/W system.

Class 1 - Emergency

There are two alarms in this class: (1) smoke

detection/fire suppression and (2) rapid cabindepressurization. (These systems arediscussed in more detail later in this section.)Class 1 is a hardware system only; its input isnot processed by any MDMs or software. Thesystem uses hardware, such as hard-wiredsensors, to monitor parameters and to issuealarms. Because of the nature of the class 1alarms, they always receive the highestpriority for resolution.

The emergency (class 1) aural alarms consistof a siren (activated by the smoke detection

system) and a klaxon (activated by the deltapressure/delta time sensor that recognizes arapid loss of cabin pressure), and they areannunciated by hardware. The siren'sfrequency varies from 666 to 1,470 hertz and

returns at a five-second-per-cycle rate. Theklaxon is a 2,500-hertz signal with an on/offcycle of 2.1 milliseconds on and 1.6 millisec-onds off, mixed with a 270-hertz signal with acycle of 215 milliseconds on and 70milliseconds off.

The emergency alarm visual cues consist ofillumination of the four MASTER ALARMpushbutton indicators on panels F2, F4, A7,and MO52J. The smoke detection system alsoilluminates SMOKE DETECTION lights onpanel L1, displays information on the SM SYSSUMM 1 display (SMOKE), and issues a

backup C/W "smoke alarm" message. Simi-larly, cabin pressure information can be seenon the SM SYS SUMM 1 display (CABIN).

Class 2 - C/W

This class also consists of two subclasses:primary C/W, which is a hardware system,and backup (B/U) C/W, which is a softwaresystem.

Panel R13

Panel R13

Limit SetValue Limit

UpperFuncSet

Lower ReadVolts

Parameter Select ParamStatusTripped

MemoryRead

ParamEnable

LampTestLeft

InhibitRightClearInhibited

(Fixed)

PROM

LimitSelectLogic

SystemTransducer

RAM

Comparator

Multiplexer

1

20

ControlLogic

1

40

30

PowerSupplyA

Master Alarm and TG' B

Caution/Warning

Electronics Unit

Backup

C/W

ComputersESS 1 BCC/W A

ESS 2 CAC/W B

PanelF7

MDM

MDMs

PowerSupplyB

Master Alarm and TG' AMaster Alarm A

Master Alarm B

ToneA

VolB

CommunicationSystem

Panels F2, F4,A7, M052J

' Tone Generator

SMALERT

Panel C3Caution/Warning

080.cvs

Panel 7

0 1 2 3 4 5 6 7 8 9

00-

01-

02-

03-

04-

05-

06-

07-

08-

09-

10-

11-

O2 PRESS H2 PRESSFUEL CELL

REACFUEL CELL

STACK TEMPFUEL CELL

PUMP

CABINATM O2 HEATERTEMP

MAIN BUSUNDERVOLT

ACVOLTAGE

ACOVERLOAD

FREONLOOP

AV BAY/CABIN AIR

IMU FWD RCS RCS JET

H2O L OOP RGA/A CCEL AIR DATA LEFT RCS RIGHT RCS

LEFT RHC RIGHT/AFTRHC

L EF T OM S R IG HT OM S

PAYLOADWARNING

GPC FCSSATURATION

OMS KIT OMS TVC

PAYLOADCAUTION

PRIMARY C/W FCSCHANNEL

MPS

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

BACKUP C/WALARM

APUOVERSPEED

APUUNDERSPEED

HYD PRESSAPU

TEMP

PA

R

A

M

E

T

ER

S

STATUSLIMIT

VOLTSX X X

MemoryRead

Clear

Panel C3Caution/Warning

MODEACK

Panel C3

ASCENT

MASTER

ALARM

X X X

(Variable)

Caution and Warning System Overview


33/663

The primary C/W system has the capacity tomonitor 120 inputs, which are received fromtransducers through either signal conditionersor flight forward MDMs. Baselined limit valuesare stored in the C/W electronics unit located inavionics bay 3. These values can be changed by

the crew, after the parameters' engineering unitsare converted to a standard voltage value,through switches on panel R13U; however, ifpower is lost, the limits will return to theiroriginal values. The majority of the originalstored values are identical to the backup C/W(software) values. Thirty-nine lights on thepanel F7 annunciator matrix are dedicated tothe primary C/W; the exception is the BACKUPC/W ALARM.

When a primary C/W alarm is issued, theappropriate lamp on the panel F7 annunciator

matrix is illuminated, all four MASTER ALARMindicators are illuminated, the C/W tonesounds, and the appropriate lamp on the panelR13U parameter status light matrix isilluminated. No CRT fault message is generated

by the primary C/W.

The primary C/W system receives power frompower supply A from the C/W A circuit breakerpowered by ESS 1BC on panel 013, and powersupply B from C/W B circuit breaker powered

by ESS 2CA on panel 013.

A loss of power supply A will cause all panel F7lights except BACKUP C/W ALARM toilluminate. It will also cause a loss of panelR13U status lights and function, smoke detec-tion via circuit test A, the CAUTION/WARNING MEMORY READ switch, lower

bulbs of the MASTER ALARM light (except forlamp test), primary C/W limit sensing, andtones to the middeck.

A loss of power supply B causes the BACKUPC/W ALARM light to come on in addition tothe primary C/W light, a loss of smokedetection via circuit test B, upper bulbs of the

MASTER ALARM lights (except during a lamptest), and sleep station headset tones.

The backup C/W (class 2) system is part of thesystems management fault detection andannunciation (FDA), GNC, and backup flightsystem software programs. Only the 69 backupC/W alarms that are produced by FDA(software that monitors parameters and initiates

alarms) have limits that can be changed anddisplayed in engineering units accessed throughthe SM TABLE MAINTENANCE specialistfunction display (SPEC 60). The remaining

backup C/W alarms that are produced by theguidance and navigation program are accessed

through general-purpose computer read/writeprocedures. A backup C/W out-of-tolerancecondition will trigger illumination of the fourMASTER ALARM lights, illuminate the redBACKUP C/W ALARM light on panel F7, anddisplay a message on the fault message line andfault summary page.

O2PRESS H2PRESSFUEL CELL

REACFUEL CELL

STACK TEMPFUEL CELL

PUMP

CABIN ATMO2HEATER

TEMP

MAIN BUSUNDERVOLT

ACVOLTAGE

ACOVERLOAD

FREONLOOP

AV BAY/CABIN AIR IMU FWD RCS RCS JET

H2O LOOP RGA/ACCEL AIR DATA LEFT RCS RIGHT RCS

LEFT RHC RIGHT/AFTRHC

LEFT OMS RIGHT OMS

PAYLOADWARNING GPC

FCSSATURATION OMS KIT OMS TVC

PAYLOADCAUTION PRIMARY C/W

FCSCHANNEL MPS

(R)

(R)

(R)

(R)

(R)

(R)

(R)

(R)

APUOVERSPEED

APUUNDERSPEED

HYD PRESSAPUTEMP

081.cvs

(R)BACKUP C/W

ALARM

(R)

(R)

(R)

Caution and Warning Annunciator Matrixon Panel F7

(The 39 lights shown are dedicated to the primary C/W System. The

BACKUP C/W ALARM light is dedicated to the entire backup C/W

system. (R) signifies a red warning light. Red lights take precedence

over yellow).

C/W Circuit Breaker on Panel 013


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The class 2 (C/W) aural master alarm isactivated by the primary (hardware) system, the

backup (software) system, or both. The C/Wtone is an alternating 375 hertz and 1,000 hertzat a 2.5 hertz rate. The alternating C/W alarmtone is generated when the hardware system

detects an out-of-limit condition on any of the120 parameters it monitors or when the software(backup) system detects a parameter that is outof limits.

Class 2 primary and backup C/W visual cuesinclude a 40-light annunciator matrix on panelF7. This matrix annunciates various system orfunctional failures. Each light is driven by oneor more parameters. With the exception of theBACKUP C/W ALARM light, once a lamp has

been illuminated, it will not be extinguisheduntil all parameters driving that light are backwithin limits. THE BACKUP C/W ALARM lightis extinguished once a MSG RESET key is pushed.

C/WCH

PARAMETERNAME

C/WCH

PARAMETERNAME

C/WCH

PARAMETERNAME

C/WCH

PARAMETERNAME

C/WCH

PARAMETERNAME

0 CRYO O2 P TK1 25 GPC 3 50 CRYO H2 P TK1 *75 100 L RHC 1 CRYO O2 HTR1 TK1 26 RCS LEAK/TK P - F 51 CRYO O2HTR 2 TK3 76 RCS TK P FU- R 101 FCS SATURATION 2 TC1 REAC O2 27 OMS ENG - L 52 FC3 REAC H2 *77 102 FC2 COOL PUMP 3 DC VOLT MAIN A 28 APU 3 EGT 53 AC3 VOLT ( A, B, C) 78 APU 2 OVERSPEED 103 IMU

4 CAB PRESS 29 MPS HE TK P - R 54 CAB N2 FLOW 1 79 MPS MANF P LH2 104 AV BAY 3 TEMP 5 GPC 1 30 CRYO O2 P TK 4/5 *55 80 CRYO H2 P TK 4/5 105 H2O LOOP 1 PUMP OUT P 6 RCS TK P OX - F 31 CRYO O2 HTR 2 TK2 56 RCS LEAK/TK P - L *81 106 FREON LOOP 1 FREON FLOW 7 OMS TK P OX - L 32 FC2 REAC H2 57 OMS ENG - R 82 FC3 STACK T 107 FREON LOOP 1 EVAP OUT T 8 APU 1 EGT 33 AC1 VOLT (

A, B, C) 58 APU 3 OIL T 83 AC3 OVLD 108 APU 2 UNDERSPEED

9 MPS HE TK P - C 34 CAB PPO2 A 59 MS HE REG P - R 84 AV BAY 1 TEMP 109 HYD 2 P 10 CRYO O2 P TK2 35 GPC 4 60 CRYO H2 P TK2 *85 110 R/AFT RHC 11 CRYO O2 HTR 2 TK1 36 RCS TK P OX - L 61 CRYO O2 HTR 1 TK4 86 RCS LEAK/TK P - R 111 FCS CH BYPASS 12 FC1 REAC H2 37 OMS TK P OX - R 62 FC1 STACK T *87 112 FC3 COOL PUMP 13 DC VOLT MAIN B 38 APU 1 OIL T 63 AC1 OVLD 88 APU 3 OVERSPEED *113

14 CAB O2 FLOW 1 39 MPS HE REG P - C 64 CAB N2 FLOW 2 *89 114 CAB HX OUT T 15 GPC 2 *40 *65 *90 115 HWO LOOP 2 PUMP OUT P 16 RCS TK P FU - F 41 CRYO O2 HTR 1 TK3 66 RCS TK P OX - R 91 ADTA 116 FREON LOOP 2 FREON FLOW 17 OMS TK P FU - L 42 FC3 REAC O2 67 OMS TVC 92 FC1 COOL PUMP 117 FREON LOOP 2 EVAP OUT T 18 APU 2 EGT 43 AC2 VOLT ( A, B, C) 68 APU 1 OVERSPEED 93 RGA/AA 118 APU 3 UNDERSPEED

19 MPS HE TK P - L 44 CAB PPO2 B 69 MPS MANF PL O2 94 AV BAY 2 TEMP 119 HYD 3 P 20 CRYO O2 P TK34 45 GPC 5 70 CRYO H2 P TK3 95 PL WARNING 21 CRYO O2 HTR 1 TK2 46 RCS TK P FU - L 71 CRYO O2 HTR 2 TK4 96 RCS JET 22 FC2 REAC O2 47 OMS TK P FU - R 72 FC2 STACK T 97 PL CAUTION 23 DC VO MAIN C 48 APU 2 OIL T 73 AC2 OVLD 98 APU 1 UNDERSPEED 24 CAB O2 FLOW 2 49 MPS HE REG P - L 74 CAB FAN P 99 HYD 1 P

Hardware Caution and Warning Table

Parameter Status Light Matrix on Panel R13U


35/663

Panel R13U is the crew's interface with theprimary C/W system. It includes a parameterstatus light matrix that is used to check thestatus of a parameter and also to checkparameter limits. When used to check the statusof parameters, the numbers on the left side of

the matrix are read first to obtain the first twonumbers of the parameter (row), then thenumber on the top is read to obtain the thirdnumber of the parameter. The matrix candisplay all 120 parameters (numbered from 000to 119) of the primary C/W system.

Class 3 - Alert

This class is a software system operated by theSM software. It would generally receive lowerpriority than a class 1 or 2 alarm. Class 3 alert isdesigned to inform the flight crew of a situation

leading up to a class 2 alarm or one that mayrequire a long procedure (over 5 minutes) inorder to rectify the problem. When an alertparameter exceeds its limits, the blue SMALERT light on panel F7 is illuminated, adiscrete is sent to the primary C/W system toturn on the alert tone, and the software displaysa fault message on the fault message line andfault summary page.

Both guidance, navigation, and control (GNC)and systems management (SM) software senseout-of-limit conditions. These software systems

also serve some less critical parameters andannunciate the systems management alert tone.The SM alert tone is a steady tone of 512 hertz ofpredefined duration generated in the C/Welectronics when activated by inputs from theonboard computers.

Class 0 - Limit Sensing

Class 0 is a software system consisting of up anddown arrows on the CRT displays next to aparameter. It provides no aural annunciation.

A down arrow displayed next to a parameterwould indicate that the low limit for thatparameter had been met or violated. In addi-tion, the down arrow is used to indicate a statethat does not agree with the nominal state; forexample, a fan that is nominally on (e.g., HUMSEP fan) is off.

An up arrow displayed next to a parameterwould indicate that the upper limit for thatparameter has been exceeded.

Smoke Detection and Fire Suppression

This emergency class 1 alarm is hardwaredriven. The crew is alerted to emergencysituations by use of visual and audio alarms.

Smoke detection and fire suppression capabili-ties are provided in the crew cabin avionics

bays, the crew cabin, and the Spacelabpressurized module. Ionization detection ele-ments, which sense levels of smoke concentra-tions or rate of concentration change, triggeralarms and provide information on smokeconcentration levels to the performance-moni-toring CRT system and an array of red SMOKEDETECTION lights on panel L1.

Smoke Detection and Fire Suppression System

The ionization detection system is divided intotwo groups: group A and group B. Group Aionization detection elements are located in theenvironmental control and life support systemcabin fan plenum outlet beneath the crew cabinmiddeck floor and in the left return air duct onthe crew cabin flight deck, and one element islocated in each of the three forward avionics

bays (1, 2, and 3A). Group B ionization detec-tion elements are located in the right return airduct on the crew cabin flight deck and inavionics bays 1, 2, and 3A. On Spacelabmissions, ionization detection elements arelocated in the Spacelab module.


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If an ionization detection element senses asmoke particle concentration of 2,000 (200)micrograms per cubic meter for at least 5seconds and/or a rate of smoke increase of 22micrograms per cubic meter per second for eightconsecutive counts in 20 seconds, a trip signal

illuminates the applicable red SMOKEDETECTION light on panel L1, illuminates thefour red MASTER ALARM lights on panels F2,F4, A7, and MO52J, and sounds the siren in thecrew cabin. The normal reading on the SM SYSSUMM 1 display for the smoke detectionelements is 0.3 to 0.4 milligram per cubic meter.A reading on the CRT of 2.0, plus or minus 0.2,corresponds to 2,000 (200) micrograms percubic meter.

After an alarm and a reset of the detector, thefollowing conditions may be observed:

If the alarm returns in 5 seconds, it isdue to the concentration exceeding 2,000 200 micrograms per cubic meter for 5seconds.

If the alarm returns in 20 seconds, it isdue to the concentration increasing at arate greater than or equal to 22micrograms per cubic meter per secondfor eight consecutive counts in 20seconds.

If the alarm returns immediately, thedetector would be suspect, and a self testshould be performed. If available, theconcentration readout should beobserved on SM SYS SUMM 1.

If the alarm does not return, perform selftest. If available, check concentration onSM SYS SUMM 1.

0001/ /078 SM SYS SUMM 1 5 000/03:13:09

BFS 000/00:00:00

SMOKE 1/A 2/B

CABIN - 0.9 DC VOLTS 1/A 2/B 3/C

L/R FD - 0.4 0.2 FC 31.1 31.1 31.1

AV BAY 1- 1.2 - 0.0 MAIN 31.0 31.1 31.0

2- 0.6 0.3 CNTL AB 29.3 29.3 29.3

3- 0.1 - 0.9 BC 29.3 29.3 29.3

CABIN CA 29.3 29.3 29.3

PRESS 14.7 ESS 29.8 29.8 29.8

dP/dT +.00 AC

BU/EQ -.00 +.00 VOLT A 117 117 117

PPO2 3.02 3.02 B 117 117 117

FAN P 5.79 C 117 117 117

HX OUT T 49 AMPS A 4.4 4.1 2.7

B 3.9 4.2 3.2

N2 FLOW 0.0 C 2.4 3.2 4.8

IMU FAN P 4.62 FUEL CELL PH

V FC1 FC2 FC3 AMPS 172 167 178SS1 15 18 18 REAC VLV OP OP OP

SS2 16 20 11 STACK T +204 +203 +203

SS3 22 26 26 EXIT T 150 150 151

TOTAL AMPS 510 COOL P 61 61 61

KW 15 PUMP

085

SM SYS SUMM 1 (DISP 78)

FIRE SUPPRESSION Switches and PushButtons and SMOKE DETECTION Lights on

Panel L1


37/663

Fire Extinguisher Locations

Fire suppression in the crew cabin avionics baysis provided by three Halon extinguisher bottlespermanently mounted in avionics bays 1, 2, and3A. Each bottle contains 3.74 to 3.8 pounds ofHalon in a pressure vessel that is 8 inches longand 4.25 inches in diameter. To activate theapplicable bottle in an avionics bay, thecorresponding FIRE SUPPRESSION switch onpanel L1 is positioned to ARM, and thecorresponding AGENT DISCH pushbuttonindicator onpanel L1 is depressed for at least 2seconds. The AGENT DISCH pushbuttonindicator activates the corresponding pyro

initiator controller, which initiates a pyrotechnicvalve on the bottle to discharge the Halon intothe avionics bay. The discharge of Halon willproduce a noise of approximately 130 decibelsin the avionics bay. The discharge will give aHalon concentration in the avionics bay of 7.5 to9.5 percent. A 4 to 5 percent concentration isrequired to suppress a fire. This concentrationwill provide protection for approximately 72

hours. When the bottle is fully discharged, thepushbutton indicator white light will beilluminated. The white light will be illuminatedif the pressure in an avionics bottle falls below60 10 psig.

Red SMOKE DETECTIONlights on panel L1 areilluminated by the following: the CABIN lightis illuminated by a smoke detection ionizationelement in the ECLSS cabin fan plenum, the LFLT DECKlight is illuminated by the crew cabinleft flight deck return air duct smoke ionizationelement, the R FLT DECKlight is illuminated by

the crew cabin right flight deck return air ductsmoke ionization element, and the PAYLOADlight is illuminated by the smoke detectionionization elements in the Spacelab pressurizedmodule. The applicable smoke detectionionization element illuminates the applicableredAV BAYlight on panel L1, activates the C/W

MASTER ALARM red light, and sounds thesiren in the crew cabin.


38/663

Fire and Smoke Subsystem Control CircuitBreakers on Panel 014



The circuit breakers that control the fire andsmoke subsystem are located on panels 014, 015,and 016. Panel 014 contains theMN A SMOKEDETN L/R FLT DKand BAY 2A/3B, FIRE SUPPRBAY 3, and ANNUN FWD ACA 1 circuit

breakers. Panel 015 contains MN B SMOKEDETN BAY 1B/3A, FIRE SUPPR BAY 1 andannunciator FWD ACA 1andACA 2/3andAFT

ACA 4/5 circuit breakers. Panel 016 containsMN C SMOKE DETN CABIN and BAY 1A/2B,FIRE SUPPR BAY 2, andANNUNCIATOR FWD

ACA 2/3andAFT ACA 4/5.

Three hand-held fire extinguishers are availablein the crew cabin. Two are located in the crewcabin middeck, and one is on the flight deck.Each fire extinguisher nozzle is tapered to fit firehole

Documents

1988 Space Shuttle Orbiter Systems Manual