BEIJING—Comac’s C919 flight-test aircraft have been grounded for modifications, costing about three months in the flight-testing schedule. The company has nonetheless restated a target to achieve certification in 2020. The two prototypes that have so far flown are having their tailplanes and flaps modified, said two industry sources. The work on the tail is specifically a response to delamination observed on the carbon-fiber reinforced plastic elevators, said one of the ...
