On July 12, 2017, about 1146 eastern daylight time, a Piper PA-28R-200, N55612, was substantially damaged during a forced landing to a levy near Pembroke Pines, Florida. The flight instructor and pilot-rated student were not injured. The airplane was being operated under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight that originated about 1112 from North Perry Airport (HWO), Hollywood, Florida.The flight instructor stated that about 30 minutes into the flight while performing a pre-maneuver checklist, the fuel selector was switched from the right to left tank position. Shortly afterwards the engine began to run rough accompanied by a loss of engine power. The fuel selector was then changed back to the original position which restored engine power. The flight instructor elected to return to HWO, and about 2 minutes after switching to the right tank, the engine lost power again, and could not be restored. He maneuvered the airplane for a forced landing on a nearby levy. According to the Federal Aviation Administration inspector who examined the airplane while it was at the accident site, two distinct marks were noted on the sloped portion off the right side of the levy. Farther along the direction of travel, a continuous mark from the left main landing gear was noted on the sloped portion off the left side of the levy. The airplane came to rest on the top of the levy with the right main landing gear collapsed, and no damage to the propeller. Although there was fuel leakage from the right fuel tank due to puncture, an adequate supply of uncontaminated fuel remained in each fuel tank. The fuel selector was found in the off position with the locking mechanism engaged and locked. With the assistance of the operator, the engine was started and operated between 600 and 2,000 rpm with the fuel selector on the left and right positions, also while exercising the fuel selector from left to right and right to left positions, with no discrepancies noted. The manifold pressure and fuel pressure were within normal limits. Checks of each magneto was performed at 2,000 rpm with each mag drop between 50 and 75 rpm. The engine was briefly run to full static rpm with the fuel selector on the left and right positions, with no discrepancies noted. Safety concerns prevented prolonged full power engine operation. During engine operation the left fuel gauge indicated 7/8 capacity, while the right fuel gauge indicated almost full. No contamination was noted in the wing fuel tanks, which were drained prior to removing the wings to facilitate recovery of the airplane. Examination of the fuel selector following recovery revealed only residual fuel remained in the fuel selector, and oily residue was noted on the outside of the selector valve rotation area. The fuel selector valve was removed and sent to NTSB for examination. Examination of the fuel selector valve revealed that movement of the shaft resulted in corresponding movement of the inner portion. The valve could be positioned to the left and right positions with no blockage noted. It also could be positioned to the off position. No further testing of the valve was performed.