Apollo 13
At five and a half minutes after liftoff, Swigert, Haise, and Lovell felt a little vibration. Then the center engine of the S-II stage shut down two minutes early. This caused the remaining four engines to burn 34 seconds longer than planned, and the S-IVB third stage had to burn nine seconds longer to put Apollo 13 in orbit.
Days before the mission, backup LM pilot Charlie Duke inadvertently exposed the crew to German measles. Command module pilot, Ken Mattingly, turned out to have no immunity to measles and was replaced by backup command module pilot Jack Swigert.
Ground tests before launch, indicated the possibility of a poorly insulated supercritical helium tank in the LM's descent stage so the flight plan was modified to enter the LM three hours early in order to obtain an onboard readout of helium tank pressure.
The No. 2 oxygen tank, serial number 10024X-TA0009 had been previously installed in the service module of Apollo 10, but was removed for modification (and was damaged in the process of removal). The tank was fixed, tested at the factory, installed in the Apollo 13 service module. and tested again during the Countdown Demonstration Test (CDT) at the Kennedy Space Center.beginning March 16, 1970. The tanks normally are emptied to about half full, and No. 1 behaved all right. But No. 2 dropped to only 92 percent of capacity. Gaseous oxygen at 80 psi was applied through the vent line to expel the liquid oxygen, but to no avail. An interim discrepancy report was written, and on March 27, two weeks before launch, detanking operations were resumed. No. 1 again emptied normally, but No. 2 did not. After a conference with contractor and NASA personnel, the test director decided to "boil off" the remaining oxygen in No. 2 by using the electrical heater within the tank. The technique worked, but it took eight hours of 65-volt DC power from the ground-support equipment to dissipate the oxygen. Due to an oversight in replacing an underrated component during a design modification, this turned out to severely damage the internal heating elements of the tank
Launched: 11 April 1970 UT 19:13:00 (02:13:00 p.m. EST)
Returned to Earth: 17 April 1970 UT 18:07:41 (01:07:41 p.m. EST).
Source: NASA
