NASA briefing on SpaceX Crew-1 / Merlin engine anomaly underway. Two engines being swapped out on that Falcon 9 first stage.

SpaceX's Koenigsmann: After GPS scrub, saw that engines I and II were starting early. Nothing immediately obvious was found, but engines were pulled and sent to McGregor.

"We were actually able to replicate it in Texas. It did the same thing on the test stand."

Led to the discovery of relief valve blockage. "Masking lacquer" leftover from build process was cause; cleaning off solved the problem.

Found more of the build-process "lacquer" on other engines, so those were removed and will be replaced with "clean" ones.

Koenigsmann explains a bit more: TEA-TEB, LOX, and kerosene all need to be introduced in the right order for smooth engine start. If not, can result in some damage. Sensor during GPS III detected chamber pressures rising too soon, meaning timing was off.

Worth noting that the parts related to the lacquer issue come from a vendor. Koenigsmann said they've informed people there; will also work to improve inspections when the part is received.

NASA's Stich lays out Crew-1 timeline:

– Crew already in soft quarantine
– Oct. 31: More stringent quarantine
– Nov. 6: Crew travels to KSC
– Nov. 9: Falcon 9 test fire
– Nov. 11: Full rehearsal
– Nov. 14: Launch
– Nov. 15: Backup opportunity at 1927 ET

Stich adds NASA would like to see GPS launch before Crew-1 due to another Merlin engine change. Not sure if he was referring to the lacquer issue or something else. That would mean SpaceX needs to fly at least twice (GPS and Sentinel-6) before Crew-1, which is in 17 days.