The first Block 5 launch earlier this year carried only a portion of the latest Falcon 9 upgrades. Included in the upgrades that had not yet been installed was an upgraded helium tank design.
The composite overwrapped pressure vessels (COPVs) store cold helium at extremely high pressure. An earlier version of the COPVs was identified as the cause of an explosion during a Falcon 9 hot fire test in 2016. The explosion completely destroyed the vehicle and the satellite it was carrying.
Following the disaster, SpaceX redesigned the COPV and reworked their loading procedures. However, to compile with NASA’s strict safety guidelines for crewed missions, SpaceX has had to again redesigned the Falcon 9 COPVs. It is this latest version that was absent from the Bangabandhu Satellite-1 launch on May 11, 2018.
Currently, the first crewed launch aboard a Falcon 9 is scheduled for December. Before NASA rubber stamps a crewed mission aboard a Falcon 9, the agency requires their SpaceX to perform at least seven launches in “crew configuration”. As the Bangabandhu launch omitted the upgraded COPV, it did not count towards that requirement.
SpaceX has since confirmed that their first launch of a “crew configuration” Falcon 9 will be in support of their Crew Dragon demo flight. The flight is currently scheduled for August leaving the provider just three months to launch an addition six times.