In July and August 1966, NASA officials conducted a customer acceptance readiness review at North American Aviation's Downey plant, issued a certificate of worthiness, and authorized spacecraft 012 to be shipped to the Kennedy Space Center. The certificate listed incomplete work: North American Aviation had not finished 113 significant engineering orders at the time of delivery.13
Mating the AS-204 spacecraft modules in the operations and checkout building, 4 January 1967.
The command module arrived at KSC on 26 August and went to the pyrotechnic installation building for a weight and balance demonstration.14 With the completion of the thrust vector alignment on 29 August, the test team moved the command module to the altitude chamber in the operations and checkout building and began mating the command and service modules. Minor problems with the service module had already showed up, and considerable difficulties with the new mating hardware caused delays.
On 7 September NASA released a checkout schedule. By 14 September, while the Saturn launch vehicle moved on schedule, the Apollo spacecraft already lagged four days behind. On the same day, a combined systems test was begun. Discrepancy reports numbered 80 on 16 September and had risen to 152 within six days. One of the major problems was a short in the radio command system. In the meantime, the test team had installed all but one of the flight panels. At Headquarters during this time, a board chaired by the Associate Administrator for Manned Space Flight, Dr. George Mueller, and made up of OMSF center directors, conducted a detailed review of the spacecraft. On 7 October this board certified the design as "flightworthy, pending satisfactory resolution of listed open items."15
The simulated altitude run, originally scheduled for 26 September, had gradually slipped back in schedule. It was run on 11 October, but plans for an unmanned altitude run on 12 October, a flight crew altitude run on 14 October, and a backup crew run on 15 October also slipped. So did the projected dates of mechanical mating of the spacecraft with the launch vehicle and the launch itself.
The unmanned altitude chamber run finished satisfactorily on 15 October. The first manned run in the altitude test chamber, on 18 October, experienced trouble after reaching a simulated altitude of 4,000 meters because of the failure of a transistor in one of the inverters. With the replacement of the inverter, the system functioned satisfactorily. The prime crew of Grissom, White, and Chaffee repeated the 16-hour run the next day with only one major problem developing in the oxygen cabin supply regulator. This problem caused a delay of the second manned run with the backup crew scheduled for 21 October. Continued trouble with the new oxygen regulator caused the indefinite suspension of the second manned test before the end of October. By this time it had become clear that the spacecraft needed a new environmental control unit. Technicians removed the old unit on 1 November.
Meanwhile, at North American Aviation's Downey plant a propellant tank had ruptured in the service module of spacecraft 017. This provoked a special test of the propellant tanks on the 012 service module at KSC. In order to conduct this testing in parallel with further checking of the command module, the test team removed the command module from the altitude chamber.16 Later they removed the fuel tanks from the service module in the chamber. After pressure-integrity tests, they replaced the tanks and returned the command module to the chamber.17 The test team installed and fit checked the new environmental control unit on 8 November and hooked up the interface lines two days later. But this did not completely solve the difficulties. Problems in the glycol cooling system surfaced toward the end of November and on 5 December forced a removal of the second environmental control unit.
The Apollo Review Board was to say of this glycol leakage several months later,
water/glycol coming into contact with electrical connectors can cause corrosion of these connectors. Dried water/glycol on wiring insulation leaves a residue which is electrically conductive and combustible. Of the six recorded instances where water/glycol spillage or leakage occurred (a total of 90 ounces leaked or spilled is noted in the records) the records indicate that this resulted in wetting of conductors and wiring on only one occasion. There is no evidence which indicates that damage resulted to the conductors or that faults were produced on connectors due to water/glycol.18The difficulties in the materials that already had arrived at KSC and the endless changes that came in from North American Aviation - 623 distinct engineering orders - presented major problems for the NASA-NAA test teams. As many workmen as could possibly function inside the command module continually swarmed into it to replace defective equipment or make the changes that NAA suggested and Houston approved. The astronauts came and went, sometimes concerned with major and sometimes with minor matters on the spacecraft.19
These difficulties at KSC and concurrent problems at Mission Control Center, Houston, forced two revisions to the schedule, one on 17 November, the next on 9 December. The test team kept up with or moved ahead of the latter schedule during the ensuing weeks. The third environmental control unit arrived for installation on 16 December.
The test teams had been working on a 24-hour basis since the arrival of the spacecraft at Kennedy, taking off only on Christmas and New Year's Day. On 28 December, while conducting an unmanned altitude run, the test team located a radio frequency communications problem and referred it to ground support technicians for correction. On 30 December a new backup crew of Schirra, Eisele, and Cunningham (McDivitt's original backup crew had received a new assignment) successfully completed a manned altitude run.20 Six major problems on the spacecraft surfaced, one in very-high-frequency radio communications; but a review board was to give a favorable appraisal not long afterward: "This final manned test in the altitude chamber was very successful with all spacecraft systems functioning normally. At the post-test debriefing the backup flight crew expressed their satisfaction with the condition and performance of the spacecraft."21
By 5 January the mating of the spacecraft to the lunar module adapter and the ordnance installation were proceeding six days ahead of schedule. The following day the spacecraft was moved from the operations and checkout building to LC-34. KSC advanced the electrical mating and the emergency detection system tests to 18 January, and these were completed that day. The daily status report for 20 January 1967 reported that no significant problems occurred during the plugs-in overall test. A repeat of the test on 25 January took 24 hours. A problem in the automatic checkout equipment link-up caused the delay. Further, the instrument unit did not record simulated liftoff - a duplication of an earlier deficiency. The schedule called for a plugs-out test at 3:00 p.m. on 26 January, a test in which the vehicle would rely on internal power. NASA did not rate the plugs-out test as "hazardous," reserving that label for tests involving fueled vehicles, hypergolic propellants, cryogenic systems, high-pressure tanks, live pyrotechnics, or altitude chamber tests.22