Letters in possible Cyrillic that a Russian M-100 engine -possibly a Katiuska from the Spanish Civil War- V-12, had engraved on the rocker covers, like the engine that has been in the School's "Engine Hangar" of Specialists from the León Air Base. (Years, 1960-?).
-At the CIH (Historical Interpretation Center) of La Sénia, in Tarragona, in its old Civil War aerodrome there is aeronautical material on display. Among it there is an M-62 Shvetsov engine package externally identified with the letters "Mockba", the same letters that carried the boxes of the Polikarpov's M-25s. It refers to the Moscow factory (Mockba). According to CIH historians, this is where the I-16s were called "Moscas" (Flies in Spanish) by derivation of the name painted on the boxes. Also by references of mechanics and pilots who lived through the war.