On June 4, 1994, at 1520 Pacific daylight time, a Cessna 172N, N734ZK, nosed over after encountering soft soil during a takeoff attempt from a field near Valencia, California. The aircraft was owned and operated by Konski Air of Van Nuys, California, and was rented by the pilot for a local area personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The aircraft incurred substantial damage. The certificated private pilot and the one passenger on board sustained minor injuries. The flight originated from the Van Nuys airport on the day of the accident at 1400 as a local area flight. In a statement to responding Los Angeles County Sheriff's deputies, the pilot said that while returning to the Van Nuys airport he experienced a compelling physiological need and landed the aircraft in an open dirt field. During the takeoff ground roll, the aircraft encountered soft soil and nosed over. In his written statement to the National Transportation Safety Board, the pilot reported that during the takeoff ground roll just prior to rotation, the engine started to run rough. The pilot reported that he aborted the takeoff and could not stop prior to encountering a plowed area of the field. The engine was removed from the aircraft and taken to an engine repair facility in Long Beach, California. The engine was installed in a test cell, where it started on the first attempt and ran smoothly throughout all normal power ranges.