(CNN) The last time anyone saw these military aircraft, US forces were pummeling Japanese targets in the western Pacific during World War II.

"Operation Hailstone" in February 1944 was a decisive victory for the US. But it came at a cost to American forces -- 40 service members were killed and more than 20 aircraft were lost

Many families had no answers on their loved ones' exact whereabouts for generations.

Now Project Recover , a nonprofit that searches for those missing in action since World War II, has found three of the missing aircraft.

A propeller was found on the sea floor in Micronesia's Chuuk State, formerly Truk Lagoon.

The downed aircraft include two SBD-5 Dauntless dive bombers and one TBM/F-1 Avenger torpedo bomber, according to the University of Delaware