On October 6, 1997, approximately 1330 mountain daylight time, a Piper PA-18-150, N83454, was substantially damaged when it impacted terrain during initial climb near Folsom, New Mexico. The private pilot was not injured. The airplane was owned by Curtis & Curtis Inc. of Clovis, New Mexico, and operated by the pilot under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local personal flight which was originating at the time of the accident. No flight plan had been filed. According to witnesses and the FAA inspector who visited the crash site, the pilot was taking off to the west from a grass strip next to, and parallel to, a dirt road. Postcrash examination of the wreckage by the FAA inspector revealed that there was no fuel in the airplane; however, the airplane had been on its back for two days before it was examined. The FAA inspector could not identify any anomalies with the airplane or the engine. The pilot reported to the Investigator-In-Charge (IIC) that there were "some bumps in the grass strip and the wind was nearly a direct cross wind." The pilot further reported that he climbed to approximately 50 feet agl and "I started to come back down and go to the north from the wind." He stated that "right before the ground I pulled up with the stick, but hit hard with the right wheel and wing." The FAA inspector reported to the IIC that the airplane impacted the terrain on its left side, damaging the left main gear and the left wing. The airplane came to rest in the inverted position. The pilot reported on his Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he had a current third class medical dated 10/01/97. An investigation by the FAA Southwestern Regional Flight Surgeon revealed that the pilot's medical, dated July 28, 1995, was expired. The Regional Flight Surgeon did determine that the pilot was examined by an appointed FAA Flight Surgeon on 10/07/97.