On September 3, 2022, about 1500 mountain daylight time, a Cessna 180, N3135D was substantially damaged when it was involved in an accident near Seeley Lake, Montana. The pilot and passenger were seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he topped the airplane off with fuel before he departed from the Vance Brand Airport, Longmont, Colorado, and flew direct to Seeley Lake Airport (S23), Seeley Lake, Montana, at a cruise altitude between 10,500 and 12,500 ft mean sea level (msl). The pilot stated that during cruise flight, he leaned the mixture aggressively to a fuel burn between 9.5 and 10 gallons an hour. Following the uneventful flight, the pilot began a descent to the airport traffic pattern, enrichened the mixture, and applied carburetor heat. While on the downwind for runway 16, he noted that he had about 10.5 to 11 gallons of fuel remaining. The pilot conducted a low approach by descending over runway 16 using an intermediate power setting to inspect the runway for wildlife. As the pilot initiated a climb and turned onto the left crosswind leg, the engine lost all power about 300 ft above ground level; he initiated a forced landing to a nearby clearing. Subsequently, the airplane impacted trees and came to rest in a nose-low attitude. Postaccident examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that both wings and fuselage were substantially damaged. Review of photos provided by the FAA showed that the bottom of the fuselage was cut open by an unknown source. The left and right fuel lines from the wing tanks also appeared to be separated consistent with impact damage. The wreckage was recovered to a secure location for further examination. Wreckage recovery personnel reported that no fuel was recovered from either fuel tank. Examination of the recovered airframe and engine revealed no evidence of any preexisting mechanical malfunction that would have precluded normal operation. The position of the fuel selector valve was in the left fuel tank position, and the handle was separated from the valve. Both fuel tanks exhibited crush damage. The leading edge and portion of the left fuel tank was torn open, and the right fuel tank appeared to be intact. The left and right fuel tank float gauges were intact and were placarded “NO TAKEOFF” for ¼ tank or less. The airplane was equipped with two 30-gallon fuel tanks of which 27.5 gallons were useable. The airplane owner’s manual states, “a red arc on the face of each indicator, warns the pilot that the respective tank is less than one-quarter full. Do not take off if the pointer is in the red arc.”