The helium COPV is submerged in LO2, so it's the oxygen that's soaking into the wrapping. I think the failure is that the oxygen is soaking into the wrapping be

The helium COPV is submerged in LO2, so it's the oxygen that's soaking into the wrapping. I think the failure is that the oxygen is soaking into the wrapping before the helium is fully pressurized, and then the metal container expands slightly and crushes the oxygen that soaked in between the metal vessel and the carbon wrapping.