APOLLO 13Safety Message

Bob SieckOdyssey Spacecraft

NASA Project EngineerApril 1970

APRIL 1970

• OUR NATION - Vietnam war dominated mood of society - Unemployment, inflation rising - Active aerospace industry • SPACE PROGRAM - Good public support - Apollo successful , high confidence & risk tolerance - Apollo program end in sight - Apollo follow on programs: - Skylab, significantly less resources than Apollo - Shuttle debated in Congress

• KSC - Robust ( 24/7 ) work environment, 3 missions in flow - Large ( 20 K + ) Government & Contractor team - Skilled team, stable procedures - Safety emphasis high, many hazardous operations, some incidents - Some end of program concern - Management–stay focused, give the workforce high quality “tools”

• SPACECRAFT CRYOGENIC SYSTEM - Service Module cryogenic tanks supply GO2 & GH2 for fuel

cells & breathing O2 * fill & drain tubes ( ground servicing), quantity gauges, pressure & temperature monitor, relief valve * heaters; 400w @ 65v DC (GSE), 80w @ 28v (fuel cell) * thermostat set to turnoff heater power @ 80 deg F * fans for mixture; 120vac, 26# wire

• LO2 TANK #2 SCENARIO - Handling incident, subjected to high loads in plant * Cleared for installation, shipped to KSC - Standard Apollo countdown demo test with cryos, unable to detank LO2 tank #2 * Suspect cause - internal drain tube (not used in flight) - Approved procedure to boil off LO2 with tank heaters * During detank, temperature visibility lost, stopped test * Continued after engineering management conference - Tank cleared for mission at final readiness review

• APOLLO MISSION Launch Count – service cryos, test heaters & fans.

Nominal mission - 10 days, - Trans Lunar injection & CSM/LM docking approx LO + 3 hrs - CSM/LM undock for Lunar landing approx LO + 4 days

Apollo 13 - explosion occurred LO + 2 days & 7 hrs - Seventh fan cycle since LO - LM activation approx 1 ½ hrs later - Crew returned @ LO + 6 days

ACCIDENT FACTORS• Technical - Thermostat switches not certified to GSE power level , contacts “arced’, stayed closed (no measurement) - Continuous ground power (8 hrs) resulted in 1000 deg F temperature at top of heater, melted fan wire insulation - Un insulated wires near metal components in O2 tank setup conditions for ignition when power applied

ACCIDENT FACTORS• Underlying Issues - Tank internal structure questionable due to factory installation handling incident - Inability to detank with standard procedure at KSC indicated internal damage - Improvised detank procedure had no prior test or certification - Performed hazardous ground operations with inadequate visibility

• ACCIDENT REVIEW BOARD FINDINGS

- Decision to fly hardware with known – unknown damage - Performed nonstandard procedures: * without verifying certification of affected hardware * without adequate visibility - Positive finding : the work authorization and documentation process was followed

• ACCIDENT REVIEW BOARD RECOMMENDATIONS - Reassess certification of all hardware, assure test requirements correctly reflect certification basis - Formalize procedure for designer approval of non standard test/operations procedures ( Bldg 45 “CHIT” system ) - Remove cryo tank fans and wiring, add separate LO2 tank

All changes implemented, less than one year impact to Apollo 14 mission

• LESSONS LEARNED - Test as you fly , fly as you test. - Most major incidents are the result of a series of events and decisions. - Non standard operations should be reviewed with a “what could go wrong” approach.

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