The Ava 4A was a low power flat-four (boxer engine) developed for very light aircraft in France in the 1930s. It was used by several prototypes and at least one production series.
Marcel Violet was a French racing driver who designed his own two-cylinder, two-stroke engines. He also designed a two stroke horizontally opposed flat-four, which was built under licence at L'agence general moteurs "Ava" by Jean Aubry of the Société J. Thibault, G Aubry et Cie, alloy metal specialists, as the Ava 4A. It only produced 25abbr=onNaNabbr=on and was intended to power small, low cost, single seat aircraft, replacing the aging Anzanis and completing with the French Mengin Type B and the older British Bristol Cherub engines.
The Ava 4A was on display at the November 1936 Paris Salon. It powered several prototypes and also the forty-six examples of the series production variant of the Farman Moustique, the F.451.
A 4A-00 survives in a private collection and is sometimes exhibited on loan.