Successive orders for the S-328 kept the aircraft in continuous production at Prague-Letnany, and when in March 1939 German troops occupied Bohemia and Moravia, dissolving the Czechoslovak Republic, the S-328 was still on the assembly lines and remained so until a total of 450 had been completed. Almost immediately after the occupation of Bohemia and Moravia, S-328s were pressed into service as trainers with the Luftwaffe's A/B-Schulen, while others were passed to the Slovak Air Force which had been established under Luftwaffe patronage. But the S-328's wartime career was not to be confined to the passive role of training. With the formation of the Störkampfstaffeln by the Luftwaffe during the winter of 1942-43, the S-328 once more achieved operational service. The Störkampfstaffeln, the forerunners of the later Nachtschlachtgruppen, were hurriedly formed to provide an answer to the nocturnal harassing of the Russian Polikarpov Po-2 biplanes, and the S-328s, among other types, were crewed by volunteers from the ranks of the instructors at the A/B-Schulen, although most of the Letovs had been supplanted by later types by the spring of 1943.
 
 
Type 2-seat trainer and light attack bomber
Engine 1  Walter-built Bristol Pegasus II.M-2
Dimensions Length 10,34 m , height 3,38 m ,  span 13,69 m , wing area  39,4 m2 (upper 20,4 lower 19) ,
Weights Empty 1680 kg, loaded  2750 kg, max. take off weight  
Performance Max.. speed  280 km/h at sea level, 328 km/h at 2000 m, cruising speed 250 km/h , range 1280 km, endurance  , service ceiling  7200 m , climb
Armament 2 fixed forward-firing 7.92 mm  machine gun vz.30 in lower wing (400 rpg)
2 7.92 mm machine gun in flexible mount in rear cockpit (420 rpg in 6 drums)
500 kg of bombs. 5  100 kg bombs (4 in pairs under the wing, 1 under the fuselage). Usually 6 x 20 kg bombs under wing and 2 x 50 kg under the fuselage.