The optional heavier models can carry more payload or fly longer routes, Boeing said.
The carrier cited the impact of the partial government shutdown.
The carrier plans to add over 250 new airplanes in the next two years.
NTSB personnel are on the scene and beginning their investigation.
The carrier will temporarily slash 5% of its total schedule.
LaGuardia Airport is closed as investigators gather at the scene.
The action centers on whether the JetBlue-United partnership violates job protections in the pilots’ contract.