The first production FB-111A aircraft (serial 67-159) flew on 13 July 1968. It was accepted by the Air Force on 30 August. A second FB-111A was delivered on 25 October. However, these two planes were powered by TF30-P-12A engines designed for Naval service instead of the Air Force P-7 turbofan. In addition, problems with the avionics subsystem slowed further deliveries, with the Air Force not accepting its next FB-111A until 23 June 1969.
