On December 30, 2006, at 1100 Pacific standard time, a Cessna 140, N9198Z, experienced a loss of control on the landing rollout and came to rest in a nose down attitude on runway 16L at Van Nuys Airport (VNY), Van Nuys, California. The pilot/owner operated the airplane under the provisions of 14 CFR Part 91. The airplane sustained substantial damage. The certified flight instructor (CFI) and the private pilot/owner under instruction were not injured. The local instructional flight departed Whiteman Airport (WHP), Los Angeles, California, about 1030, with a planed destination of Van Nuys. Visual meteorological conditions prevailed and no flight plan had been filed. In a written report to the National Transporation Safety Board, the CFI stated that the purpose of the flight was to provide conventional landing gear (tail dragger) flight training to the pilot/owner. The pilot/owner had recently purchased the airplane and needed to obtain a tailwheel endorsement. The CFI indicated that the pilot under instruction had full flight control authority of the airplane on the flight and landing. During the landing rollout, the pilot under instruction was still operating the airplane; it veered to the right, and the CFI applied left rudder in an attempt to return to runway centerline. As the airplane continued off the runway towards an airport sign, the brakes were applied. The nose dropped, the propeller blades struck the runway, and the airplane came to rest on its nose. The owner, who was undergoing instruction, also submitted a written report to the Safety Board. He stated that the airplane was moving from the left to right during the landing roll. He believed it was the CFI that overcorrected the airplane and then "pushed a little to hard on the brakes," which put the airplane up on its nose. Both pilots reported no preimpact mechanical malfunctions or failures with the airframe or engine. The accident was reported the Safety Board on February 4, 2007, following routine maintenance survelliance by a Federal Aviation Administration (FAA) airworthiness inspector. The FAA airworthiness inspector examined the airplane and noted structural damage to the firewall and adjacent structural members.