The pilot was carrying out a survey flight of his property to locate a vehicle. The aircraft was observed by ground witnesses, near the vehicle, to commence a descending right hand turn with the apparent intention of landing in a cleared paddock adjacent to the one in which the vehicle was located. The aircraft appeared to lose altitude suddenly after it had completed about 270 degrees of the turn and the right wing touched the ground. The aircraft cartwheeled to a stop. The pilot survived the accident but is unable to remember anything about it. It is probable that the pilot was concentrating his attention on either the ground party or the intended landing area and he allowed the aircraft to either stall or unintentionally lose height. The wing struck the ground before the pilot was able to take action to recover the aircraft to level flight.