Complex sentence: After assembly, operations in Finland were limited to test flights and, in September 1941, combat flights with the fighters were prohibited, although the aircraft were maintained on the roster until they were retired and scrapped on 30 December 1949.
Split into simpler sentences: After assembly, operations in Finland were limited to test flights and, in September 1941, combat flights with the fighters were prohibited. The aircraft were maintained on the roster until they were retired and scrapped on 30 December 1949.