On August 20, 2008, approximately 1800 central daylight time, a single-engine, Cessna 182 airplane, N92780, was substantially damaged upon impact with terrain following a loss of engine power, during an approach to the Caldwell Municipal Airport (RWV), Caldwell, Texas. The commercially rated pilot and passenger both received serious injuries. The airplane was registered and operated by Farney Aviation Management Corp. Georgetown, Texas. Visual meteorological conditions prevailed and an instrument flight plan was filed for the 14 Code of Federal Regulations Part 91, cross-country flight originating from Sugar Land Regional (SGR) airport, Houston, Texas about 1700, and destined for Waco Regional (ACT) airport Waco, Texas. According to reports, the pilot reported an engine problem and was attempting to land at the Caldwell airport. A Federal Aviation Administration (FAA) Inspector, who responded to the accident site, reported that the airplane was largely destroyed by the impact. During the forced landing, the airplane collided with a light pole and came to rest in a baseball field. There was not a post-crash fire. There were no reports of any injuries to persons on the ground. The FAA inspector conducted the on-scene examination and provided site photographs. Once the on-site inspection was complete, the airplane was recovered to a secure facility for further examination. On August 28, 2008 the NTSB Investigator-in-charge and technical representatives from the airframe and engine manufacturer examined the wreckage at the salvage yard. The fuel selector valve was found turned to the "both" position. The airplane's Continental engine was modified under a STC (Supplemental Type Certificate) by Texas Skyways, Inc. to model O-470 UTS. A visual inspection of the engine was preformed and the engine crankshaft rotated; continuity through the engine was confirmed and a thumb compression test preformed. The spark plugs appeared "normal" and had light gray deposits. The magneto's produced "spark" at each terminal. The throttle control linkage to the carburetor was still attached. The fuel screens in the carburetor and gascolator were clear and free of contaminates. The oil filter was removed and opened; the filter element was clear of metal deposits. The inspection of the engine failed to identify any abnormalities that would have prevented normal operation. A portable GPS unit mounted in the airplane was downloaded; a review of the data reveals the airplane's departure from the Georgetown Municipal Airport (GTU) with about a one-hour, twenty minute flight to SGR. The last route shown on the GPS was the airplane's departure from SGR, until its accident near RWV, approximately 58-minutes later. Prior to its departure from GTU, the airplane was filled with 24.72 gallons of fuel. An airport security camera recorded the airplane being refueled. A review of the security video disclosed that the pilot, after refueling, did not put the right wing's fuel cap back on. Photographs taken at the accident site, shows that the left wing's fuel cap in place; however, the right wing fuel cap is located (on the ground) approximately 4-feet in front of the wing. The photo's also show two main areas of "blue streaks" on the airplane; on the right side fuselage behind the rear fuselage window, and below the right horizontal stabilator. The blue streaks are consistent with (blue) 100LL aviation fuel "running" back onto the airplane.