Evolved from the experimental S-28 of 1929 and the S-228 of 1931, the S-328 had been designed to meet a Finnish requirement, although, in the event, no Finnish order for the type materialised. However, the Czechoslovak Ministry of National Defence became interested in the type, and, in 1934, the S-328 had been ordered into production as the Czechoslovak Air Force's standard reconnaissance aircraft. Powered by a Walter-built Bristol Pegasus II.M.2 nine-cylinder radial rated at 635 hp at sea level and 580 hp at 5,000 ft (1 524 m), the S-328 was a sturdy all-metal aircraft with fabric covering apart from the light metal fuselage upper decking. Armament normally comprised two fixed forward-firing 7,92-mm machine guns in the wings and a pair of similar weapons on a swivelling Skoda mounting in the observer's cockpit, and racks could be attached beneath the fuselage and lower wings for up to 1,000 lb (500 kg) of bombs. Maximum speed ranged from 174 mph (280 km/h) at 5,900 ft (1800 m) to 158 mph (255 km/h) at 16,400 ft (5 000 m). An altitude of 16,400 ft (5 000 m) was attained in 17 min, service ceiling was 23,620 ft (7 200 m), and range with standard fuel was 435 miles (700 km), but this could be extended with overload tanks to 795 miles (1 280 km).
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.
S-328 BB+DI A/B 32 Pardubitz nov 1941
S-328 PM+XB A/B 13 Pilsen march 1941