A Piper PA-31T, N9162Y, and a Beech 200C, N390AC, were involved in a midair collision while both were cruising at 17,500 ft in unlimited visibility. The Piper was tracking inbound on the 210 deg radial of the Richmond VOR. The Beech was tracking inbound on the 340 deg radial of the Wilmington VOR. Both aircraft were substantially damaged, but both aircrew were able to continue flying and land safely. The pilot of the Piper said that he saw a tan flash just before the collision. The pilot of the Beech did not see the Piper. The cockpit view of the PA-31 pilot was somewhat restricted by the left windshield side post. Likewise, the Beech pilot's view was somewhat restricted by the windshield center post and the windshield wiper arm. The aircraft converged on one another with a closure speed of about 420 kts and in the same general directions that the pilots' views were obstructed.