On May 1, 1998, approximately 1500 Pacific daylight time, a Piper PA-28-160, N5157W, collided with rough terrain during a forced landing off the approach end of FirstAir Field, Monroe, Washington. The certified flight instructor and the student pilot were not injured, but the aircraft, which was owned by the student, sustained substantial damage. The 14 CFR Part 91 instructional flight, which departed Harvey Field, Snohomish, Washington, about 30 minutes earlier, was being operated in visual meteorological conditions. No flight plan had been filed, and there was no report of an ELT activation. According to the instructor, while approximately 4,000 feet AGL, he pulled out the mixture control until the engine stopped firing in order to simulate an engine failure in flight. Then as the student maneuvered toward FirstAir Field, the instructor occasionally "cleared" the engine by returning the mixture to the full rich position. After turning onto a close-in final approach, with the mixture still pulled nearly all the way out, the student raised the nose of the aircraft a few degrees, and the propeller stopped turning. The instructor then returned the mixture control to the full rich position, and told the student to engage the starter. According to the instructor, the student attempted twice to get the propeller to rotate using the starter, but there were "no results." When the engine did not start, the instructor pushed the nose down to prevent a stall, and the student completed a landing in an area where the terrain had been torn up by construction crews. Just after touchdown, the aircraft collided with the rough/uneven terrain created by the construction. In a post-accident interview, the instructor said that in the past he had always used the throttle to simulate an engine failure (instead of the mixture), and was not sure why he had used the mixture this time instead. A post-accident inspection of the engine revealed no anomalies, and using the battery that was in the aircraft at the time of the accident, the engine was successfully started on the first attempt and run to 1,500 rpm. A higher rpm run was not attempted because of the vibrations generated by the bent propeller.