SP-4011 Skylab: A Chronology

 

[401-403] APPENDIX 6

SYSTEM REPAIRS AND MAINTENANCE

 

[From Johnson Space Center, Skylab Mission Report, Supplement 3, Flight Crew Contributions to the Skylab Mission, July 1974]

 

 

System

Abnormal condition

Corrective action

Unplanned Tasks

Structure

Orbital Workshop micrometeorite shield (thermal control)

Shield torn off during launch, resulting in high interior Workshop temperature.

Skylab parasol deployed through solar scientific airlock on first visit.

 

Twin-pole sunshade deployed during extravehicular activity on second visit.

Electrical power

Orbital Assembly solar array system

Solar-array system wing 2 broken off during launch and wing 1 failed to deploy.

 

Wing 1 deployed during EVA on first visit.

 

Orbital Assembly charger/battery/regulator module 15

Stuck relay in regulator prevented battery from being charged.

Crewman freed stuck relay during first visit by striking skin of spacecraft with hammer in vicinity of relay during EVA.

 

Attitude control

Orbital Assembly rate-sensing system

Deterioration in performance of rate gyros during first visit.

Rate gyro "six-pack" installed in multiple docking adapter on second visit. Installation required extravehicular operations.

Environmental control

Thermal control system

Leakage of coolant fluid from coolant loop.

 

Fluid replenished on third visit.

Refrigeration system

Failed primary and secondary refrigeration system loop bypass valves in partial radiator position caused low loop temperature and loss of control.

 

Connector J5 disconnected to permit simultaneous use of primary and secondary loops and to prevent automatic switchover.

Apollo telescope mount control and display panel cooling system

Gas bubbles in cooling fluid caused flow rate fluctuations.

Spare liquid/gas separator installed in place of system filter.

 

Airlock module primary coolant loop

Contamination caused temperature control valve to stick in cold position.

Valve resumed operation during troubleshooting.

 

Life support

Orbital Workshop hatch check valves

 

Check valves leaked.

Check valve orifices taped.

Orbital Workshop vent valve

Vent valves remained open after close commands sent.

Valves purged and cleaned; valves then closed.

 

150-psi nitrogen pressure regulator

Nitrogen pressure regulator was 10 to 15 psi low.

Placed on a 5-day duty cycle; operated normally.

 

Urine receptacle suction Iine

Rubber washer loose.

New washer supplied and installed by crew.

Communications

Transmitter

Transmitter C inoperative.

Crewman reset circuit breaker on panel 200 and operations were normal.

 

Airlock Module tape recorder

Tape slipped off capstan.

Crew repositioned tape on capstan.

 

Television camera

Television camera color wheel was not rotating, causing loss of lower part of picture and partial color.

 

Crew removed lens and started wheel manually to remove contamination in gearing.

 

Teleprinter

 

Printout difficult to read.

Teleprinter head cleaned.

 

Planned Tasks

Life support

Molecular sieves A and B partial pressure carbon dioxide

Erratic readings.

 

A and B sensors replaced. O-ring on molecular sieve B partial pressure carbon dioxide inlet and cap replaced.

 

Condensate dump

Dump probe iced up.

 

Dump probe replaced.

 

Waste management compartment water dispenser

 

Low water flow.

 

Replaced with spare.

 

Waste management compartment squeezer

 

Leaked around seal.

 

Seal replaced.

 

Airlock Module electrical power system

Fine sensor control panel

Panel 392 failed test.

Sensor replaced with spare.

Communications

Television input station

 

Broken connector pin on television input station 642.

 

Replaced with spare.

 

Television monitor

 

No video on television monitor.

 

Monitor and monitor cable replaced.

 

Television power cable

 

Coaxial lead failed in power cable.

 

Power cable replaced.

 

Airlock Module tape recorder

 

Three recorders failed.

 

Replaced with spares.

 

Teleprinter

 

Paper feed mechanism inoperative.

 

Teleprinter head assembly replaced with spare unit.

 

Speaker- intercommunications assembly

 

Switch failures on two units.

 

Assemblies replaced with spares.

 

Video tape recorder

 

Recorder failed to transmit recorded signals.

 

Electronics unit and transport unit replaced with spares.

 


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