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Apollo Expeditions to the Moon

CHAPTER 13, Appendix

Detailed Chronology From 2.5 Minutes
Before The Accident To About 5 Minutes After

GET * 
55:52:31Master caution and warning triggered by low hydrogen pressure in tank No. 1.
55:52:58CopCom (Charlie Duke): "13, we've got one more item for you, when you get a chance. We'd like you to stir up your cryo tanks. In addition, I have shaft and trunnion-"
55:53:06Swigert- "Okay."
55:53:07"-for looking at the Comet Bennett, if you need it."
55:53:12Swigert- "Okay. Stand by."
55:53:18Oxygen tank No. 1 fans on.
55:53:19Oxygen tank No. 2 pressure decreases 8 psi.
55:53:20Oxygen tank No. 2 fans turned on.
55:53:20Stabilization control system electrical disturbance indicates a power transient.
55:53:21Oxygen tank No. 2 pressure decreases 4 psi.
55:53:22.718Stabilization control system electrical disturbance indicates a power transient.
55:53:22.7571.2-volt decrease in cic bus 2 voltage.
55:53:22.77211.1-amp rise in fuel cell 3 current for one sample.
55:53:36Oxygen tank No. 2 pressure begins rise lasting for 24 seconds.
55:53:38.05711-volt decrease in ac bus 2 voltage for one sample.
55:53:38.085Stabilization control system electrical disturbance indicates a power transient.
55:53:41.17222.9-amp rise in fuel cell 3 current for one sample.
55:53:41.192Stabilization control system electrical disturbance indicates a power transient.
55:54:00Oxygen tank No. 2 pressure rise ends of a pressure of 953.8 psia.
55:54:15Oxygen tank No. 2 pressure begins to rise.
55:54:30Oxygen tank No. 2 quantity drops from full scale for 2 seconds and then reads 75.3 percent.
55:54:31Oxygen tank No. 2 temperature begins to rise rapidly.
55:54:43Flow rate of oxygen to all three fuel cells begins to decrease.
55:54:45Oxygen tank No. 2 pressure reaches maximum volue of 1008.3 psia.
55:54:51Oxygen tank No. 2 quantity jumps to off-scale high and then begins to drop until the time of telemetry loss, indicating from 2.5 minutes be re failed sensor.
55:54:52Oxygen tank No. 2 temperature reads -151.30 F.
55:54:52.703Oxygen tank No. 2 temperature suddenly goes off-scale low, indicating failed sensor.
55:54:52.763Last telemetered pressure from oxygen tank No. 2 before telemetry loss is 995.7 psia.
55:54:53.182Sudden accelerometer activity on X, Y, Z axes.
55:54:53.220Stabilization control system rate changes begin.
55:54:53.323Oxygen tank No. 1 pressure drops 4.2 psi.
55:54:53.5002.8-amp rise in total fuel cell current.
55:54:53.542X, Y, and Z accelerations in CM indicate 1.179, 0.65g, and 0.659.
55:54:53.555Loss of telemetry.
55:54:53.555+Master caution and warning triggered by dc main bus 8 undervoltage. Alarm is turned off in 6 seconds. All indications are that the cryogenic oxygen tank No. 2 lost pressure in this time period and the panel separated.
55:54:54.741Nitrogen pressure in fuel cell 1 is off-scale low indicating failed sensor.
55:54:55.350Telemetry recovered.
55:54:56Service propulsion system engine valve body temperature begins a rise of 1.65 F in 7 seconds. Dc main bus A decreases 0.9 volt to 28.5 volts und dc main bus B decreases 0.9 volt to 29.0 volts. Total fuel cell current is 15 amps higher than the final value before telemetry loss. High current continues for 19 seconds. Oxygen tank No. 2 temperature reads offscale high after telemetry recovery, probably indicating failed sensors. Oxygen tank No. 2 pressure reads offscale low following telemetry recovery, indicating a broken supply line, a tank pressure below 19 psi, or a failed sensor. Oxygen tank No. 1 pressure reads 781.9 psia und begins to drop.
55:54:57Oxygen tank No. 2 quantity reads off-scale high following telemetry recovery incdicating failed sensor.
55:55:01Oxygen flow rates to fuel cells 1 und 3 approached zero after decreasing for 7 seconds.
55:55:02The surface temperature of the service module oxidizer tank in bay 3 begins a 3.8 F increase in a 15-second period. The service propulsion system helium tank temperature begins a 3.8 F increase in a 32-second period.
55:55:09Dc main bus A voltage recovers to minutes after 29.0 volts; dc main bus 8 recovers to 28.8.
55:55:20Swigert: "Okay, Houston, we'ye had a problem here."
55:55:28Duke: "This is Houston. Say again, please."
55:55:35Lovell: "Houston, we've had a problem. We've had a main B bus undervolt.
55:55:42Duke: "Roger. Main B undervolt."
55:55:49Oxygen tank No. 2 temperature begins steady drop lasting 59 seconds, indicating failed sensor.
55:56:10Haise: "Okay. Right now, Houston, the voltage is - is looking good. And we had a pretty large bang associated with the caution und warning there. And as I recall, main B was the one that had an amp spike on it once before."
55:56:30Duke: "Roger, Fred."
55:56:38Oxygen tank No. 2 quantity becomes erratic for 69 seconds before assuming an off-scale-low state, indicating failed sensor.
55:56:54Haise: "In the interim here, we're starting to go ahead und button up the tunnel again."
55:57:04Haise: "That jolt must have rocked the sensor on - see now - oxygen quantity 2. It was oscillating down around 20 to 60 percent. Now it's full-scale high."
55:57:39Master caution und warning triggered by dc main bus B undervoltage alarm is turned off in 6 seconds.
55:57:40Dc main bus B drops below 2 25 volts und continues to fall rapidly.
55:57:44Lovell: "Okay. And we're looking at our service module RCS helium 1. We have - B is barber poled und D is barber poled, helium 2, D is barber pole, und secondary propellants, I have A und C barber pole." Ac bus fails within 2 seconds.
55:57:45Fuel cell 3 fails.
55:57:59Fuel cell current begins to decrease.
55:58:02Master caution und warning caused by ac bus 2 being reset.
55:58:06Master caution und warning triggered by dc main bus A undervoltage.
55:58:07Dc main bus A drops below 26 25 volts und in the next few seconds levels oft at 25.5 volts.
55:58:07Haise: "Ac 2 is showing zip."
55:58:25Haise: "Yes, we got a main bus A undervolt now, too, showing. Its reading about 251/2. Main B is reading zip right now."
56:00:06Master caution und warning triggered by high hydrogen flow rate to fuel cell 2.

* GET: Ground Elapsed Time
(hours, minutes, seconds)