Production. A-31 ("Vengeance") dive bombers. Spark-plug installation. Workers are installing spark plugs in the powerful Wright "double cyclone" engine used in the Vultee "Vengeance" dive bomber manufactured at Vultee's Nashville Division. Note the partially completed "Vengeance" in the background. The "Vengeance" (A-31) was originally designed for the French. It was later adopted by the RAF (Royal Air Force) and still later by the U.S. Army Air Forces. It is a single-engine, low-wing plane, carrying a crew of two men and having six machine guns of varying calibers