recycle ?

[bobby_hamill]

i just saw on the Science Channel documentary called "Engineering Catastrophes" where they were
talking about the Apollo 13 oxygen tank explosion .I Don't know how accurate the information is ,but it was said
on the show that the oxygen tank used on the Apollo 13 was first used on the Apollo 10 mission .

I never thought in the early days of the space program that any space craft parts would be reused on later space craft.

Bobby

 

[lakeroadster]

The tank in question was in the Service Module. The Service Module remained in space, the Command Module came back to Earth. When the orbit of the Service Module decayed, it re-entered the atmosphere.... and burned up.

 

[Steve Shannon]

i just saw on the Science Channel documentary called "Engineering Catastrophes" where they were
talking about the Apollo 13 oxygen tank explosion .I Don't know how accurate the information is ,but it was said
on the show that the oxygen tank used on the Apollo 13 was first used on the Apollo 10 mission .

I never thought in the early days of the space program that any space craft parts would be reused on later space craft.

Bobby

I think they meant that that design of tank was first used In Apollo 10, not that the actual tank was recycled.

 

[Antares JS]

Apollo 15, on display at the USAF Museum in Dayton, is displayed with its door shut because the interior was gutted for reuse on Apollo 16.

 

[mikec]

I think it was pulled out of a previous spacecraft before that one flew and then got reused.

 

[Funkworks]

"Apollo 13’s big problem centered around the second of the two oxygen tanks—called, appropriately enough, "tank no. 2." The spherical tank had been manufactured years earlier by Beech Aircraft under contract to North American Rockwell, and it was originally fitted to the Apollo 10 service module in 1969. Some time before Apollo 10’s launch, the tank was removed from the Apollo 10 service module for maintenance or modification, and it was dropped. It fell from a height of about two inches.

Rather than re-use a potentially damaged tank, another was fitted to Apollo 10. Meanwhile, the dropped tank was inspected and no damage was found. However, the external inspection missed one red flag. Internally, a fill line suffered slight damage."

https://arstechnica.com/science/201...osion-and-six-hours-of-live-saving-decisions/

 

[OverTheTop]

Interesting article but it failed to mention the root cause of the problem. There was a change from a lower voltage (maybe 24V) to higher voltage operation of the power buses in the entire system that had failed to be communicated to one of the subcontractors. The thermal cutout that welded shut during the testing was not rated for the higher DC voltage and current, and hence welded shut when it operated. I can't rememeber if this was due to lower heater resistance (higher current) or lack of capability of the thermal cutout. Whichever it was resulted in the cutout welding closed and keeping the heater on, and the rest is history.

FYI, switching DC is much harder on contacts than switching AC as the current doesn't go to zero at any time so any arc formed is maintained for much longer. That's why DC ratings of switches are almost always far less than the AC current rating.

 

[Sandy H.]

Interesting article but it failed to mention the root cause of the problem. There was a change from a lower voltage (maybe 24V) to higher voltage operation of the power buses in the entire system that had failed to be communicated to one of the subcontractors. The thermal cutout that welded shut during the testing was not rated for the higher DC voltage and current, and hence welded shut when it operated. I can't rememeber if this was due to lower heater resistance (higher current) or lack of capability of the thermal cutout. Whichever it was resulted in the cutout welding closed and keeping the heater on, and the rest is history.

FYI, switching DC is much harder on contacts than switching AC as the current doesn't go to zero at any time so any arc formed is maintained for much longer. That's why DC ratings of switches are almost always far less than the AC current rating.

Wow, I had no idea. As a person who believes they follow the space program closely, it is amazing to know that such a major/minor mistake was the root cause is jaw dropping. The article mentioned being connected to 65 VDC ground power vs. 28 VDC design power, but as a fan-boy, things like that seem impossible, but actually occurred. In fairness, when working in my own area of expertise, I screw up too, so it is so important to see how a 'small' failure can lead to a catastrophic result and hold yourself to the highest standard. Even then, I never knew about the voltage issue, which means my study of history is too low of a standard.

Thanks for pointing that out. I need to step up on my research of things that are important to me.

Sandy.

 

[OverTheTop]

Wow, I had no idea. As a person who believes they follow the space program closely, it is amazing to know that such a major/minor mistake was the root cause is jaw dropping. The article mentioned being connected to 65 VDC ground power vs. 28 VDC design power, but as a fan-boy, things like that seem impossible, but actually occurred. In fairness, when working in my own area of expertise, I screw up too, so it is so important to see how a 'small' failure can lead to a catastrophic result and hold yourself to the highest standard. Even then, I never knew about the voltage issue, which means my study of history is too low of a standard.

Thanks for pointing that out. I need to step up on my research of things that are important to me.

Sandy.

There is a lot out there and I guess sometimes you just get lucky what you happen to read. Don't beat yourself up too much .

[edit] Yes, small details can really matter, and small variations can be good process indicators showing that something needs more attention. That is something I try to keep in mind when dealing with faultfinding things at work and home.

 

[Funkworks]

Interesting article but it failed to mention the root cause of the problem. There was a change from a lower voltage (maybe 24V) to higher voltage operation of the power buses in the entire system that had failed to be communicated to one of the subcontractors. The thermal cutout that welded shut during the testing was not rated for the higher DC voltage and current, and hence welded shut when it operated. I can't rememeber if this was due to lower heater resistance (higher current) or lack of capability of the thermal cutout. Whichever it was resulted in the cutout welding closed and keeping the heater on, and the rest is history.

The article then says:

“NASA assigned the seemingly undamaged tank to fly in Apollo 13’s service module. Extensive testing took place again prior to launch, and during one test, the tank couldn’t be properly purged of liquid oxygen (this was done by feeding gaseous oxygen into the tank to push the liquid oxygen out; the damaged fill line made that impossible). The testing team decided to empty the tank by heating it up and forcing the liquid oxygen to boil off.

Here, a significant mistake occurred.

The tank’s heater—normally used to keep the tank’s temperature and pressure elevated to facilitate the flow of oxygen—had been designed to accept power from the spacecraft’s 28-volt DC system, but it was connected to the ground’s 65-volt DC system for eight hours. The high-voltage current welded the heater switches closed, preventing automated shut-off, and the temperature in the tank rose to more than 1,000 degrees Fahrenheit. The tank’s internal thermometer could display a maximum temperature of only 80 degrees Fahrenheit. Nothing external indicated a problem.

This overnight bake-in did the job of emptying the tank, but it also caused an unknown amount of damage to the tank’s internals. A NASA report suggests that "serious damage" was done to the Teflon insulation coating the tank’s internal wiring.”

 

[OverTheTop]

The article then says:

“NASA assigned the seemingly undamaged tank to fly in Apollo 13’s service module. Extensive testing took place again prior to launch, and during one test, the tank couldn’t be properly purged of liquid oxygen (this was done by feeding gaseous oxygen into the tank to push the liquid oxygen out; the damaged fill line made that impossible). The testing team decided to empty the tank by heating it up and forcing the liquid oxygen to boil off.

Here, a significant mistake occurred.

The tank’s heater—normally used to keep the tank’s temperature and pressure elevated to facilitate the flow of oxygen—had been designed to accept power from the spacecraft’s 28-volt DC system, but it was connected to the ground’s 65-volt DC system for eight hours. The high-voltage current welded the heater switches closed, preventing automated shut-off, and the temperature in the tank rose to more than 1,000 degrees Fahrenheit. The tank’s internal thermometer could display a maximum temperature of only 80 degrees Fahrenheit. Nothing external indicated a problem.

This overnight bake-in did the job of emptying the tank, but it also caused an unknown amount of damage to the tank’s internals. A NASA report suggests that "serious damage" was done to the Teflon insulation coating the tank’s internal wiring.”

I had read that but the actual root cause was the contractor not being notified of the voltage change. Also nobody checked the heater used was actually acceptable on the newer, modified system. The same heaters as were provided earlier were provided for the upgraded electrical system.

 

[Funkworks]

I was looking to answer whether the same tank had been used on Apollo 10 and the first article that popped-up seemed pretty good.

I just found what seems to be the official report, but I haven't read it.
https://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_13_review_board.txt