Fwd: 40 Year Anniversary of the Joint Apollo Soyuz Mission

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: July 21, 2015 at 8:06:41 AM CDT
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: 40 Year Anniversary of the Joint Apollo Soyuz Mission

In AmericaSpace Part 3 it discusses what happened during reentry, see yellow highlight. The problem that almost caused loss of the crew could have been avoided if they would have used the post Apollo 15 & Skylab reentry procedures. See my discussion below as this information does not appear anywhere else.  

 

Prior to the mission Flight Operations Crew Training and Procedures engineer John F. Whitley informed the Sequential Subsystem Manager Gary W. Johnson that the Commander Tom Stafford who had also commanded the Apollo 10 mission had insisted that the checklist be as it was for Apollo 10 in regards to the Earth Landing System (ELS) AUTO/MANUAL switch position. That is to be in the "MANUAL" position until 30,000 foot altitude instead of being placed in the "AUTO" position which allows for ground verification prior to reentry blackout. Previously the crews were concerned that the guarded ELS LOGIC switch might fail arming the ELS prematurely. After Apollo 10 a change was made to rewire the ELS LOGIC Switch on Panel 1 to have series as well as parallel redundancy, eliminating this single-point-failure (SPF) mode of the switch and the affectivity was Apollo 15 and subsequent including the Skylab CSMs. The crew procedures were changed to have the ELS AUTO/MANUAL switch to be in the AUTO position thereby allowing auto deploy of drogues and mains and for MCC to confirm switch is in the AUTO position prior to reentry blackout. John Whitley arranged for us to have a meeting with Tom Stafford so I could explain to him the changes we had made to eliminate the SPF with the switch, the Apollo 15 and subsequent missions had flown in this Auto position and this allowed the MCC to confirm the chutes could be deployed automatically. Tom insisted they would not forget to deploy the parachutes and refused to change the procedure.

As the spacecraft was descending the Commander, who was reading the checklist, failed to tell the Command Module Pilot, ELS AUTO/MANUAL switch to AUTO. The crew then saw that the spacecraft was well below the deployment altitude and proceeded to manually deploy the chutes. Drogues at 18,550 feet verses auto at 23,500 feet and Mains at 7,150 feet verses auto at 10,500 feet. The RCS system was not disabled manually (RCS CMD switch to OFF). The RCS CMD to OFF occurred at 16,000 feet verses checklist 24,000 feet. The cabin pressure relief valve opened automatically at 24,500 feet.  During a 30-second period of high thruster activity after drogue parachute deployment, a mixture of air and propellant combustion products followed by a mixture of air and Nitrogen Tetroxide Oxidizer (N2O4) vapors were sucked into the cabin. One of the positive roll thrusters is located only two feet away from the steam vent that pulls in outside air when the cabin relief valve is open. This exposed the crew to a high level of N2O4 as emergency oxygen masks were not available till landing. Pilot passed out and the Commander quickly put the oxygen mask on him and he was revived.  The exposure resulted in a two week hospital stay for the crew after landing.

<AmericaSpace 40 Years Since Apollo-Soyuz.docx>

<AmericaSpace -ASTP Part 3.docx>