Loggers made the discovery on private property near Rockaway Beach earlier this week.
Tillamook County Sheriff Todd Anderson said the Pentagon was concerned about possible remains of two veterans whose families would need to be notified.
According to Anderson, the aircraft was discovered on private logging land about a half mile inland between the towns of Wheeler and Rockaway beach.
Crews saw a wing, tail section, landing gear and debris from the Curtiss SB2C Helldiver in a heavily wooded area, OSP reported. The debris field was spread out over about 200 yards.
OSP and defense department officials were concerned about preserving the site until their investigation could be finished. A bomb disposal team said there was no evidence of any explosives.
Investigators were looking into whether the plane crashed on a military mission or was later purchased by someone prior to the crash.
Officials from the Joint Prisoner of War / Missing in Action Accounting Command (JPAC) in Honolulu and Navy Region Northwest were also investigating pending any human remains are found.