The non-instrument rated pilot departed Imperial, CA on 4/18/84 at about 1845 PST. Two people reported that at 2100 to 2200 PST, they saw an aircraft circling in the area of Cummings Mountain, about 10 miles south of the accident site, but because the mountain tops were obscured with clouds and rain, the aircraft disappeared. When the aircraft did not arrive at its destination, a search was begun which lasted 9 days, but the aircraft was not found at that time. However, the wreckage was discovered on 8/28/84 where it had crashed at an elevation of 3300 feet MSL. On the date of the accident, the area forecast for the vicinity of the crash site was for broken to overcast clouds at 2000 to 3000 feet MSL with tops at 16,000 feet. An exam of the crash site revealed that the aircraft had impacted in a steep right bank, slightly nose low attitude. No preimpact part failure or malfunction was found.