5 decal variants:
1. Bücker 131B, Swiss AF, Lst, FL.Kp.55, Januar 1945
2. Bücker 131B, Spain AF, Tablada 1937
3. Bücker 131B, D-EBZE, Berlin Rangdorf 1937
4. Bücker 131B, Bulgarian AF, Airfield Sofia-Bozuriste 1940
5. Bücker 131B, Finnish Aeroclub, 1940
During 1936, was produced Bü 131B with powerful 105hp Hirth HM 504A-2 engine. Most produced was the version D. The aircraft was used by Luftwaffe as training, also by night ground-attack. Was also exported in many countries - Japan, Switzerland, Spain, Yugoslavia, Romania and Bulgaria. Under licence was built in Japan and after WWII also in Spain-CASA and Czechoslovakia as C-104 trainer with Walter Minor 4-III.