Production aircraft began rolling off the line in the autumn of 1930, starting with Number 39 (39 is a designation, it was not the 39th production aircraft) in August, which passed tests on September 9, being flown by Gustaitis himself. Three more were completed by October, 1931. The second series, starting in the spring of 1931 incorporated the following changes: fuselage lengthened by 1/2 meter, larger fuel tanks installed, and turning rudders installed on all except Number 33 & Number 40. In early 1931 the ANBO III was flying with a
Walter Mars I, a nine-cylinder
radial engine. The Czech-built engines started showing signs of failure after fewer than 200 hours, so British engines were procured. One
Armstrong Siddeley Mongoose was ordered and tested on Number 48. This was the same weight as the Mars I and proved reliable so 4 more were ordered between 1934 and 1935. Six
Armstrong Siddeley Genet Major were ordered for the
ANBO V. ==Operators==