Technical issue scrubs SpaceX commercial crew launch

A last-minute problem with a rocket ignition system halted a Falcon 9 launch of a NASA commercial crew mission Feb. 27, delaying the launch by at least three days. Launch controllers halted the countdown for the launch of the Crew-6 mission about two and a half minutes before its scheduled 1:45 a.m. Eastern liftoff because of a problem with the ignition system, which uses a chemical combination called triethylaluminum triethylborane, or TEA-TEB. The launch director informed the four-person crew in the Crew Dragon of the issue a few minutes earlier. More

(Source: SpaceNews - Feb 27)