The pilot reported that, during approach, he was distracted by the right front seatback falling forward and interfering with his view of the airplane's control panel. He added that he tried numerous times to push the seatback upright, but it would not stay in the upright position. During final approach, he reached over to try to latch the seat belt to secure the seatback in an upright position. The airplane landed hard and porpoised. The airplane sustained substantial damage to the fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The automated weather observation system located on the accident airport reported that, about the time of the accident, the wind was from 200° at 13 knots, gusting to 17 knots. The pilot landed on runway 22.