Test flying, despite two aircraft substantially damaged in accidents, was completed on August 25, 1980, when the first variant of MD-80, the JT8D-209-powered MD-81 (or DC-9-81), was certified under an amendment to the FAA type certificate for the DC-9.
As probas de voo, a pesar de que dous avións resultaron considerablemente danados en accidentes, completáronse o 25 de agosto de 1980, cando a primeira variante do MD-80, o MD-81 equipado cos motores JT8D-209 (ou DC-9-81), certificouse baixo unha modificación da certificación da FAA para o DC-9.