On April 23, 2006, about 1245 Pacific daylight time, a Christen Industries, Inc., A-1, N96088, collided with power lines while maneuvering at a low altitude near Creston, California. Thereafter, the pilot flying the impact-damaged airplane made a forced landing in a rough open field, adjacent to a road. The right main landing gear separated from the airframe, right wing structure was deformed, and the airplane was substantially damaged. Neither the commercial pilot nor passenger was injured during the personal flight. The pilot had borrowed the airplane from a private individual, who was the airplane's registered owner. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from San Luis Obispo, California, about 1210. The pilot verbally reported to the National Transportation Safety Board investigator that the engine started running slightly rough while he was cruising about 500 feet over the ground. The pilot reacted to the situation by performing a precautionary landing in an open field. During the approach, he did not observe that power lines obstructed the airplane's flight path. The pilot subsequently provided a written statement to the Safety Board investigator in which he further described facts related to the accident flight. In pertinent part, the pilot indicated that during the flight he had been performing "aerial reconnaissance over the land and was not near any people or structures during the portion of...flight that was at approximately 500 feet above ground level." Less than a mile from the site of the crash, the airplane's engine began running rough and he was unable to maintain altitude. After checking the magnetos, fuel and carburetor, the pilot proceeded toward the most suitable landing area and established a shallow rate of descent with 30 degrees of flaps. The pilot further reported that he used the power available to land the airplane as slow as possible. Approximately 50 feet above the ground, the airplane collided with power lines that, according to the pilot, he had "overlooked." The pilot did not indicate that prior to the mishap he had experienced any mechanical malfunction with the airplane. In an incident report completed by the San Luis Obispo Sheriff's Office, responding officers interviewed the pilot. The report indicates the pilot acknowledged that after takeoff he flew directly toward the vicinity where the accident occurred "because he had friends that were setting up a dual sport motorbike course (in the area)." The passenger in the airplane was also interviewed by the officers. She twice reported to the officers that the engine problem began "after the pilot hit a power line...not prior to [hitting it]." A representative from Pacific Gas and Electric Company stated to Safety Board investigators that the impacted power line was 35 to 38 feet above ground level. Another representative stated the power line was 100 yards from where the airplane came to rest in the field. Under the direction of the Safety Board investigator, two Federal Aviation Administration certified mechanics, holding inspection authorization, examined the airplane. They reported finding no evidence of any preimpact mechanical malfunction with the airframe or engine, and no contaminants were found in the oil or fuel.