Major Frank M. Ross wasn't in the 366th Fighter Squadron , but in the 365th . He had been in the squadron since it was formed in Richmond, Virginia, January 1, 1943.
About the 11 April mission, here is that I have from the book " THe 365th Fighter Squadron in ww II " by Ken Miller.
Mission #51. Lt Col. Wells led a dive-bombing mission from 1650 to 1957. First target was the airfield at Gael, with hangars, buildings, and runways were hit. Next was the field at Rennes, where hangars, gun emplacements, and the control tower were damaged, but the 367th lost a pilot to flak. The 365th then flew to the base at St-Jacques and ran into heavy ground fire. Major Frank M. Ross was killed when his P-47 crashed near the field after being damaged by flak, while Capt. John W. Dickson's aircraft exploded over the field after a direct flak hit. Lt. Gsell's ship was also badly damaged, but he managed to make a successful crash-landing after returning to England. To finish the mission off, a pair of 365th pilots caught a Ju 88 on the deck near Mordelles and shot it down.
I have 2 pictures of Maj. Ross and a another one of Capt. Dickson.
I'll send them in a PM if you are interested.