SpaceX has completed its investigation into what caused an engine failure during the Falcon 9 launch on July 11. The company has filed an “accident report” with the Federal Aviation Administration (FAA) and is ready to get the Falcon 9 rocket flying again tomorrow.
The company’s investigation team, working with the FAA, was able to determine that the July 11 failure was caused by a liquid oxygen leak that developed during the initial burn of the Falcon 9’s second-stage engine. It says the leak originated from a crack in a pressure sensor sensing line that is part of the rocket’s oxygen system. A clamp that normally restrains the sensing line had come loose, subjecting it to excessive engine vibrations that eventually caused it to fatigue and crack.
The liquid oxygen leak in the upper stage of the Falcon 9 rocket caused “excessive cooling of engine components, particularly those associated with supplying ignition fluid to the engine,” according to a Statement on SpaceX websiteInstead of a controlled second burn, the engine experienced what SpaceX describes as a “hard start,” damaging it and causing the upper stage to lose altitude control.
The Falcon 9 first stage performed as expected during the July 11 launch and landed safely for reuse, but the second stage incident caused the Starlink satellites carried by Falcon 9 to deploy into a lower orbit where “an enormous drag environment” caused all 20 to re-enter Earth’s atmosphere and hopefully burn up.
To allow the Falcon 9 to fly again as soon as possible, SpaceX engineers will simply remove the failed sensing line and sensor on the second stage engine. “The sensor is not used by the flight safety system and can be replaced by alternative sensors already present on the engine.” The company has also inspected, cleaned and replaced some of the sensing lines and clamps on its “active booster fleet.” SpaceX has already tested the changes at its facility in McGregor, Texas, under FAA oversight.
Now that the investigation is complete, the Falcon 9 rocket is no longer grounded and can return to service. company website SpaceX is targeting July 27 at 12:21 a.m. ET for its next Falcon 9 launch carrying 23 Starlink satellites from NASA’s Kennedy Space Center, with additional launch window opportunities available later in the day and on July 28.