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Based on the aborted launch on Thanksgiving 2013 of the first Falcon 9 v1.1 from Florida, we know that an issue occurred where oxygen got into the ground based TEA-TEB sources.

I understand that TEA-TEB are pyrophoric , which means they combust on contact.

SpaceX reported they replaced the gas generator on the center engine.

This sounds like they might have experienced the issue on the center engine.

What I was wondering, do they ignite the center engine with pyrophorics, and then the other 8 all ignite, since there is a 145,000lb thrust fire going on just feet away? Or do they use TEA-TEB on all 9 engines during ignition?

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    $\begingroup$ I know this is an old article but it bugs me that the answer is wrong. TEA and TEB are NOT hyperbolic. As a matter of fact, they are stored together. They are pyrophoric - igniting on contact with oxygen or other oxidizer. $\endgroup$
    – user13822
    Commented Mar 19, 2016 at 11:23

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Yes, they use TEA-TEB (Triethylaluminum-Triethylborane) as their first stage ignitor and this mixture is pyrophoric (i.e. hypergolic in contact with oxygen, be it atmospheric or LOX), but no, they don't ignite one engine and let that one ignite all the others, they would want to ignite them all at once. Problem with one engine igniting others is that doing so would create a pressure spike that would likely damage the engine and, according to Ben Brockert, CEO of Able Space Co., Denver:

The fire would then travel up into the engine where it would create a massive pressure spike, definitely destroying the engine and possibly destroying engines nearby. In propulsion testing the euphemism for this is a "hard start" leading to "rapid unplanned disassembly".

Quote source and more information via Joseph Abbott's Joe Science blog post: The TEA-TEB glitch: Can't light a Falcon 9 without a spark

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  • $\begingroup$ Unfortunately that blog (or rather that entire domain) now seems intentionally broken for anyone in EU: "451: Unavailable due to legal reasons We recognize you are attempting to access this website from a country belonging to the European Economic Area (EEA) including the EU which enforces the General Data Protection Regulation (GDPR) and therefore access cannot be granted at this time." $\endgroup$
    – Dan Mašek
    Commented Nov 12, 2018 at 11:26
  • $\begingroup$ Link as retrieved from Internet Archive Wayback Machine: web.archive.org/web/20180410094343/http://www.wacotrib.com/… $\endgroup$
    – BlueCoder
    Commented Dec 17, 2018 at 11:26

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