On February 28, 2022, about 1253 central standard time, a Cessna 208B airplane, N108RF, was substantially damaged when it was involved in an accident near Campbellton, Texas. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight. The pilot reported that he started the day at San Marcos Regional Airport (HYI) and flew east toward Houston for a survey. This flight lasted about 1 hour 10 minutes. He then flew 1 hour southeast and started a second survey. After about 3 hours of total flight time, he proceeded to Pleasanton Municipal Airport (PEZ) to get fuel. During the descent, the “left fuel low” light illuminated, and shortly thereafter the “reservoir fuel low” light illuminated. The pilot ensured the fuel tanks, fuel pump, and igniters were on, and he diverted to a nearby private strip. Soon after, the airplane’s engine began to lose power. The pilot increased the throttle, but the engine lost total power. The airplane descended rapidly when it struck several trees and touched down on an upsloping field short of the runway. The wing spar in the airplane’s right wing sustained substantial damage. During a telephone conversation, the pilot reported that he last refueled the airplane the day before the accident at Ozona Municipal Airport (OZA). He then flew the airplane a little over 1 hour to HYI to prepare for the accident flight. When asked if the airplane ran out of fuel, the pilot replied “no, I should have had more fuel.” During an on-scene examination by a Federal Aviation Administration inspector, the airplane was moved to level ground. Its electrical system was turned on and the “LT fuel low,” “RT fuel low,” and “reservoir fuel low” lights illuminated. In addition, the left and right fuel gauges showed ‘empty.’ Both the left and right fuel tanks were sumped and no fuel was noted. About 2 cups of fuel were drained from the reservoir fuel tank, and a couple ounces of fuel were drained from the fuel strainer. The operator reported that once the airplane was repaired, fuel was added to both the left and right fuel tanks. The engine started and operated normally with no anomalies noted. In the Air Traffic Mandatory Occurrence Report, air traffic control (ATC) reported that the pilot declared a mayday and attempted to divert to an airport. After the airplane landed in the field, the pilot contacted ATC and reported that he “lost track of fuel and ran out.”