Failure cause
This is an initial assessment. Working with USAF and NASA on flight data, which revealed first stage was nominal. Dragon continued to communicate until it went over horizon after failure. Dragon could have been saved with right software. now including contingency software to allow Dragon to save itself. The Dragon continued to communicate until below horizon. "Parachute would have saved Dragon."
We analysed a lot of data, took 0.893 seconds before first sign of trouble and end of data. Preliminary data arose from a strut in the second stage liquid oxygen tanks that was holding down one of the pressure vessels in LOX tank. Preliminary data arose from a strut in the second stage liquid oxygen tanks that was holding down one of the pressure vessels in LOX tank. The strut was holding down a composite helium bottle used to pressurize the stage. One of those struts broke free inside the tank. Musk: at ~3.2 g, strut holding down He tank snapped, released lots of He into LOX tank. buoyancy increases in accordance w/ G-load. One of the struts appears to have snapped, releasing lots of helium into LOX tank. Preliminary conclusion is that a COPV (helium container) strut in the CRS-7 second stage failed at 3.2Gs.
Data shows a drop in the helium pressure, then a rise in the helium pressure system. Quite confusing. strut failed at 1/5th rated force, no evidence of damage to it in close-out photos before launch. One strut broke free. Tank gets buoyant in flight; @ 3.2Gs strut holding helium appears to have snapped, releasing helium. As helium bottle broke free and pinched off manifold, restored the pressure but released enough helium to cause the tank to fail. it was a really odd failure mode. Investigation still 'speculative' at this point. Helium release caused overpressure of O2 stage.
Will not use this particular struts and will test the future struts individually. Will increase cost, but not very significantly. going to individual testing of struts. Some additional cost as a result, but won’t be passed along in the price. We'll no longer use these struts & we'll no longer trust strut certify, we'll test them 1 by 1. Modest cost increase, zero price effect. strut issue is fairly straightforward, switching to something with higher level of performance.
The investigation is now showing any other issues. But looking at everything to see if there were any near misses. no sign of any other issues with the launch, looking still for any misses. May have become complacent over last few years.
and even the guy far left who has the Hitler hair do.