Apollo 11 Final Countdown LH2 Leak That Could Have Changed History

At T-8 hours 15 minutes the loading of cryogenic propellants began onto the Saturn V. Starting with the S-IVB, Liquid Oxygen was loaded followed by the S-II and S-IC. Upon completion of LOX loading, LH2 was loaded into the S-II and then the S-IVB. This was scheduled to be completed by T-3:38 at which time the astronauts could begin ingressing into the Apollo Command Module.

Here is the Public Affairs Officer's announcement.

This is Apollo Saturn Launch Control; T minus 3 hours, 4 minutes, 32 seconds and counting. Right on time as far as the astronaut countdown is concerned, the prime crew now departing from their crew quarters here at the Kennedy Space Center. Astronauts Neil Armstrong, Buzz Aldrin, and then finally Michael Collins plus their suit technicians and Director of Flight Crew Operations, Deke Slayton, now boarding the transfer van for the trip to the launch pad. The trip in the transfer van should take some 15 minutes or so to reach the pad, at which time the astronauts board the first of two elevators for the trip to the 320-foot level at the launch pad where they will then proceed to ingress the spacecraft. We logged the departure from the building at about 6:27 a.m. EDT. The transfer van now departing from the Manned Spacecraft Operations Building at the Kennedy Space Center on the start of its 8-mile trip to Launch Pad A at Complex 39 where the Saturn V launch vehicle, now fully loaded with propellants, going through preliminary checkouts. This is Launch Control.

All was going smoothly until The S-IVB LH2 loading was entering its final phase, replenish. A major leak was detected on the 200 foot level of the LUT which required the console operators to issue a Revert which stopped flow of hydrogen to the vehicle and drained the lines between the LUT and the S-IVB stage.

This is Apollo Saturn Launch Control; T minus 2 hours, 45 minutes, 55 seconds and counting. As the prime crew for Apollo 11, astronauts Neil Armstrong, Michael Collins, and Edwin Aldrin, are on the terminal part of their trip to the launch pad in the transfer van, it’s now making the curve toward pad. We have discovered a problem at the launch pad itself as the crew is about to arrive. We have a leak in a valve located in a system associated with replenishing liquid hydrogen for the third stage of the Saturn V launch vehicle. We have sent a team of 3 technicians and a safety man to the pad and these technicians are now tightening bolts around the valve. Once the technicians depart, we will send hydrogen again through the system to assure that the leak has been corrected. The astronauts now coming up toward the pad itself as the crew of several technicians at the 200-foot level proceed to tighten some bolts around a leaking valve. The astronaut team which has just arrived at the pad, the transfer van now backing up toward the elevator. In a matter of 5 minutes or so, we’ll be ready for the spacecraft commander, Neil Armstrong, to come across the sill at the 320-foot level. That is our status at 2 hours, 43 minutes, 47 seconds and counting. This is Launch Control.

A Red Crew led by LH2 engineer Jack Kramer was dispatched to the Pad to attempt to stop the leak and the astronauts proceeded to enter the Spacecraft. Steve Coester was responsible for directing and documenting their work from the Firing Room LH2 console.

Here is the location of the leaking valve.

This is Apollo Saturn Launch Control; T minus 2 hours, 40 minutes, 40 seconds and counting. At this time, the prime crew for Apollo 11 has boarded the high-speed elevator from inside the A level of the mobile launcher which is the second level inside the launcher. This is the high-speed elevator; 600 feet [180 metres] per minute, which will carry them to the 320-foot [98-metre] level, the spacecraft level. Shortly, we'll expect astronauts Neil Armstrong and Michael Collins to come across Swing Arm 9, the Apollo access arm, and proceed to the White Room and stand by to board the spacecraft. The third member of the crew, astronaut Edwin Aldrin, will be the last one to board the spacecraft, will stand by in the elevator seated in a chair while his two comrades first board the spacecraft. Once Armstrong, who sits in the left-hand seat, and Collins, who will sit in the right-hand seat during lift-off are aboard, then Aldrin will be called and he will take his seat, the middle seat in the spacecraft. The spacecraft commander Neil Armstrong and the Command Module Pilot Michael Collins now proceeding across the swing arm into the small White Room that attaches at the spacecraft level. In the meantime, about 100 feet [30 metres] below, we have a technician - a team of technicians working on a leaking valve which is a part of the Ground Support Equipment, a part of the system that's used to replenish the fuel supply for the third stage of the Saturn V rocket. He is proceeding to tighten a series of bolts around this valve in the hope that this will correct the leak. Once the technicians do depart, the hydrogen will again be flowed through the system to assure that the leak has been corrected. The spacecraft Commander Neil Armstrong and CMP, the Command Module Pilot Mike Collins, now standing by in the White Room. T minus 2 hours, 38 minutes, 45 seconds and counting; this is Launch Control.

This is Apollo Saturn Launch Control; T minus 2 hours, 10 minutes, 35 seconds and counting. At the 320-foot level, the fourth astronaut aboard the spacecraft regretfully leaves at this time. Astronaut Fred Haise is about to come out after giving the three prime crewmen a hand in their preliminary checkouts aboard. Fred Haise will be coming out shortly. In the meantime, 120 feet [37 metres] below, where we have that problem with the leaking valve, the technicians have completed their work and they are in the process now of departing from the launch pad. In a short while, we'll start flowing hydrogen again back through the general replenishing system to continue the top-off - the supply of the hydrogen fuel in the third stage of the Saturn V launch vehicle. The spacecraft commander Neil Armstrong has completed a series of checks called abort advisory system checks. This is where certain key crewmen on the ground, members of the launch team, can send signals to the spacecraft - commander in the spacecraft; light cues that would indicate a difficulty during the flight in which he could take abort action if he determined that such action was necessary. These checks have been completed and Neil Armstrong confirmed that the lights came on in the console in front of him, the panel in front of him as these lights were operated from the ground here in the Launch Control Center. All still going well with our count. We will stand by as we again bring hydrogen back to the third stage. We'll see how that operates. We're now at T minus 2 hours, 9 minutes, 4 seconds and counting; this is Kennedy Launch Control.

The Red Crew led by engineer Jack Kramer completed the repair work of the leaking valve and departed the Pad. Liquid Hydrogen flow was resumed and unfortunately the leak continued. The Red Crew returned to the Pad and with no further repair work that could be done decided to warm the valve and stop the leak by pouring water from the emergency shower and eyewash station over the valve warming it from the -423 degree hydrogen temperature. The valve had not leaked prior to introducing LH2 so it was hoped warming would stop the leak from reoccurring. While this could stop the leak it also disabled the critical replenish valve that was needed to maintain the S-IVB at the 100% fuel level required to send the astronauts from Earth orbit toward the Moon.

(After the successful launch the replenish valve was disassembled and it was discovered that the bonnet bolts which held the actuator to the body of the valve were too long and had bottomed out preventing complete compression of the bonnet gasket. At warm temperatures the valve didn't leak but when chilled it did. This information was provided by Jack Kramer)

Without a full LH2 load the launch could not proceed and would have to be scrubbed so the LH2 console team in the Firing Room had to come up with a different way to flow into the S-IVB and maintain 100% fuel level.

Steve Coester who was manning the S-IVB LH2 Loading console, call sign C4HU had been directing the troubleshooting and now suggested that the faulty replenish valve could be manually bypassed and using the high flow S-IVB LH2 fill valve in its reduced position, it should be possible to maintain the correct fuel level. The problem with this approach was the fill valve flowed at 1200 gpm and the replenish flow rate only had to be about 80-100 gpm. With no other option, it was decided to bypass the automated loading computer (PTCS) and use the high flow valve manually controlled.

So for the last one and a half hours of the countdown Jack Kramer who had returned from the Red Crew and was manning the LH2 LUT Components console operated the S-IVB Fill Valve open to reduced position and closed as directed by Steve Coester who could read the S-IVB LH2 tank level on his console. This was successfully accomplished until T-3minutes and six seconds when flow was terminated and the tank pressurized for flight.

Here is Jack Kramer (4th in) on CPH2 and Steve Coester (2nd in) on C4HU.

If the leak hadn't been stopped and proper LH2 level maintained the

Moon launch would have been scrubbed for at least July 16 and

probably for several days.

This is Apollo Saturn Launch Control; T minus 1 hour, 50 minutes, 55 seconds and counting. We're proceeding with the countdown with the Apollo 11 mission at this time and it's going satisfactorily. At this point, the spacecraft commander Neil Armstrong in the process of working the Emergency Detection System test. This is a check of the Emergency Detection System working with the launch crew here in the firing room and also the spacecraft team in control rooms back at the Manned Spacecraft Operations building here at the Kennedy Space Center. All going well with these tests at the present time. We're flowing hydrogen back into the third stage of the Saturn V launch vehicle after having difficulty with that leaking valve. It appears that we are bypassing the use of the valve directly in loading the hydrogen aboard, but we are getting the hydrogen back in to replenish the supply. All appears to be going well at this time. Weather is Go. We're coming up on 1 hour and 50 minutes. This is Kennedy Launch Control.

Here is the countdown procedure change that Coester wrote to accomplish the revised LH2 loading plan.