On 17 April 1934, the prototype conducted its maiden flight at Hatfield Aerodrome, Hertfordshire. Flown by senior de Havilland test pilot H.S. Broad, it was powered by a pair of Gypsy Six engines. Even prior to the prototype's first flight, plans to proceed with serial production of DH.89 had already received the go-ahead from management. During May 1934, airworthiness trials commenced at RAF Martlesham Heath using the prototype; during one such flight, upon attaining a speed of roughly , the tip of the aircraft's nose buckled. In response to this event, a maximum permissible speed of was implemented for all DH89s. Upon the conclusion of trials, the prototype was sold.