The Morane-Saulnier M.S.331 was the designation given to a version of the unsuccessful M.S.330 trainer powered by a Lorraine 7Me radial engine in place of the Salmson engine used in the original aircraft.
How to cite this article:
Rickard, J (13 March 2012), Morane-Saulnier M.S.331 , http://www.historyofwar.org/articles/weapons_morane_saulnier_MS331.html