On February 19, 2018, about 1730 Chamorro standard time, a Cessna 172N airplane, N7328F, was substantially damaged when it was involved in an accident at the Francisco C. Ada/Saipan International Airport (PGSN), Obyan, Northern Mariana Islands. The pilot and passenger sustained minor injuries. The airplane was operated as a Title14 Code of Federal Regulations Part 91 aerial observation flight. According to the operator, about 5 minutes after departure, the pilot reported that the engine began running roughly and then lost all power when the airplane was about 3 miles east of the airport and about 2,000 ft mean sea level. The pilot contacted a tower controller at the departure airport and reported that he intended to return to the airport, and the controller instructed him to enter the left downwind leg of the traffic pattern. While returning to the airport, the pilot was able to regain engine power by pumping the throttle control. While approaching the left downwind leg, the engine began to run roughly again, and the power decreased to 1,000 rpm. The pilot continued to pump the throttle control to no effect. Subsequently, the pilot declared an emergency, and a tower controller cleared him to land on an 8,700-ft-long, dry, asphalt runway. Due to the airport traffic in the area, the pilot chose to conduct a straight-in approach, instead of a 360° turn to lose altitude. According to a tower controller, the airplane was high and fast as it crossed the runway threshold and landed with about 1,000 ft of runway remaining. After landing, the airplane bounced several times, and the pilot subsequently deliberately veered it off the runway. Subsequently, the airplane impacted a ditch and nosed over. The pilot reported that he did not visually check the fuel in the tanks before departure. He subsequently reported that he did not recall whether he looked at the fuel quantity indicators before or during the flight. The pilot did not report if he conducted any preflight fuel planning. The operator reported that the fuel logs did not indicate that the airplane had been fueled on the day of the accident. The airplane’s previous flight times and fuel records were not obtained during the investigation. Examination of the airplane revealed that the wings, vertical stabilizer, and rudder had sustained substantial damage. No fuel was found in the tanks or the carburetor bowl during examination. A small amount of fuel was found in the gascolator bowl. No obvious stains or other evidence was found at the accident site indicating that fuel had leaked from the airplane. The gascolator was clear of debris. No fuel was found in the carburetor bowl. Examination of the engine and airframe revealed no evidence of any preaccident mechanical malfunctions or failures that would have precluded normal operation.