On March 2, 2016, about 1600 mountain standard time, a Piper PA-22-150 airplane, N4356A, executed a precautionary landing onto a sandy wash following a partial loss of engine power near Fountain Hills, Arizona. The private pilot and passenger were not injured; and the airplane sustained substantial damage to the wings. The airplane was registered to, and operated by, a private party as a 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The local flight originated from Phoenix-Mesa Gateway Airport (IWA), Phoenix, Arizona at about 1540. The pilot reported that after a normal preflight and run-up, he took off and circled a nearby mountain before descending to about 750 feet above the ground at a 2,400 RPM. As they followed a nearby river, the engine started to sputter and decrease to about 900 RPM; the pilot increased and decreased the throttle several times, but the engine never went above 1,200 RPM before it decreased again. He observed that the oil pressure was low; therefore, he attempted to switch fuel tanks, turned on carb heat, ensured the mixture was full rich, but the engine never responded. The pilot elected to land the airplane onto a dry wash. When the airplane touched down, the right main landing gear sunk into the dirt and the airplane made a sharp turn to the right. The airplane rolled along the dirt, impacted a tree, and came to rest nose down. During a postaccident examination by a Federal Aviation Administration Inspector, the engine cowling was removed and no visual anomalies were noted with the engine. The propeller and spinner were removed; and a test run propeller and temporary fuel tank were installed. The engine was started and operated normally; slowly, the power was increased to 2,400 RPM and the oil pressure was normal. After operating for a short time, the power was decreased and the engine was shutdown. There were no anomalies noted that would have precluded normal operation.