The FAA says SpaceX failed to file required launch collision-avoidance data ahead of a Falcon 9 launch with a batch of Starlink satellites last August.
Propulsive efficiency gains could diminish for bigger turbofans unless nacelle drag can be reduced. Flight tests show promise from a short inlet design.
More carriers, mainly ones from outside the U.S., and their trade groups are voicing concerns with FAA's plan to require 5G-related radio altimeter upgrades.