Musk pointed to a subtle design change and a lapse in qualification testing as the cause of three sticky check valves in the Dragon thruster system that prompted a one-day delay in the supply vessel’s scheduled March 2 rendezvous with the space station. All three valves were forced open with the rapid uplink of a software change that increased pressure in the system.SpaceX was not made aware of the design change by its supplier, and while company’s engineers conducted a pre-mission low-pressure functionality test of the hardware, they elected to skip a high-pressure test that might have revealed the problem, he said.“It was kind of the spacecraft equivalent of the Heimlich maneuver that got the valve unstuck. It was definitely a worrisome time,” Musk said. “Now, obviously [we] and the supplier are extremely sensitive to even nuanced changes.”
HA! So it's another contractor-supplier communication issue that caused all that trouble on the Dragon......
Quote from: Galactic Penguin SST on 04/02/2013 05:48 amHA! So it's another contractor-supplier communication issue that caused all that trouble on the Dragon...... Do you care to clarify what you mean by your HA and ?This is not exactly news, if you listened to the press conference.
Quote from: Lars_J on 04/02/2013 06:30 amQuote from: Galactic Penguin SST on 04/02/2013 05:48 amHA! So it's another contractor-supplier communication issue that caused all that trouble on the Dragon...... Do you care to clarify what you mean by your HA and ?This is not exactly news, if you listened to the press conference.It's a common point of failure in engineering that large and small companies have fallen on - so SpaceX is certainly not immune to this (and maybe another reason for in-house engineering, as they do). I'm just noting this observation..... And I didn't listen to the conference (it's late at night at where I live, plus I was busy covering the Soyuz that day), nor I have seen this being explicitly mentioned clearly on NSF, hence my post.
QuoteSpaceX was not made aware of the design change by its supplier, and while company’s engineers conducted a pre-mission low-pressure functionality test of the hardware, they elected to skip a high-pressure test that might have revealed the problem, he said.
SpaceX was not made aware of the design change by its supplier, and while company’s engineers conducted a pre-mission low-pressure functionality test of the hardware, they elected to skip a high-pressure test that might have revealed the problem, he said.
Quote from: Galactic Penguin SST on 04/02/2013 05:48 amQuoteSpaceX was not made aware of the design change by its supplier, and while company’s engineers conducted a pre-mission low-pressure functionality test of the hardware, they elected to skip a high-pressure test that might have revealed the problem, he said.Would anyone have any insight whether this would be a component-level low-pressure test of each delivered valve, or pre-launch acceptance testing for the assembled Dragon?cheers, Martin
... Why the valves passed vendor acceptance testing and a low-pressure test on the assembled system but failed in flight is an interesting question.
Here is the (zipped) mp3 file of the March 27th SpaceX/NASA teleconference:http://www.gamefront.com/files/23148885/SpaceX+Post-Landing+Teleconference+March+27+2013.zip
And the transcript (from Trent):http://shitelonsays.com/transcript/crs-2-post-landing-teleconference-2013-03-27
Quote from: yg1968 on 04/03/2013 01:57 pmAnd the transcript (from Trent):http://shitelonsays.com/transcript/crs-2-post-landing-teleconference-2013-03-27Transcript is of Elon only.
Quote from: QuantumG on 04/03/2013 10:53 pmQuote from: yg1968 on 04/03/2013 01:57 pmAnd the transcript (from Trent):http://shitelonsays.com/transcript/crs-2-post-landing-teleconference-2013-03-27Transcript is of Elon only.I modified to include Gwynne's line as well.
Do you two run the site? It's awesome.
Quote from: Jason1701 on 04/09/2013 06:00 amDo you two run the site? It's awesome.Anyone can edit. I made the site, thanks.
