At least 61 Tutors were produced, with a rate of seven per month in early 1940, as part of Greece's preparations after the outbreak of World War II.

Preparations for the production of the PZL P.24, the main fighter used by the Greek Air Force at the time, as well as the Henschel Hs 126K-6 light bomber (for which an order of 90 units had been made to KEA) were never completed due to the outbreak of the Greco-Italian War in October 1940.

Thus, the only KEA-produced type that saw action in World War II was the 621 Tutor (in addition to training, a number was incorporated in combat squadrons as liaison aircraft).

Production also covered other areas, including refitting captured aircraft, manufacturing bombs, and specialized parts and tools.

After the war, KEA divisions produced a number of gliders but it eventually focused on maintenance work for the Greek Air Force with only limited construction activity - which went to the Hellenic Aerospace Industry (HAI) when the latter was founded.