HISTORY OF FLIGHTOn November 12, 2016, about 1640 mountain standard time, a Piper PA 28-235 airplane, N9398W, struck a berm during a forced landing, following a loss of engine power near Taylor, Arizona. The certified flight instructor and student pilot were not injured, and the airplane sustained substantial damage The airplane was privately owned and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The local flight originated from Taylor about 1600. The flight instructor reported that the preflight inspection was uneventful. The wing tip fuel tanks were both filled to half of their capacity, and the fuel tanks in the right and left wing contained 18 and 20 gallons of fuel respectively. About 40 minutes after takeoff, and after completing a series of training maneuvers with the student, the instructor decided to demonstrate an emergency descent. He asked the student to look for an appropriate simulated landing spot, and he pitched the nose slightly down, configuring the airplane for a best glide descent speed. They began the maneuver at an elevation of about 8,000 ft (1,700 agl), and after descending about 500 ft the instructor sensed that something was not right. He lifted off his headset, and the engine sounded quiet; he then pushed the throttle forward, but the manifold pressure gauge remained static, and the engine did not respond. He turned on the electric fuel pump, switched the fuel selector valve from the left to right tank, and set the fuel mixture to full rich, with no change. He then moved the throttle back and forth a few more times with no response. Concerned that they did not have sufficient altitude for further troubleshooting, he began to look for an emergency landing site. On final approach he secured the airplane by shutting off the fuel selector valve, and as they got closer to the ground he could see a berm and fence obstructing the landing area. They were unable to deviate, and during the ground roll the airplane struck the berm, bounced back into the air, and landed hard. The airplane sustained substantial damage to the aft fuselage and right side of the stabilator during the impact. AIRCRAFT INFORMATIONThe last maintenance event was for an annual inspection, on September 17, 2015, 7.1 flight hours before the accident. The airplane was powered by a normally aspirated, O-540-B4B5 engine. It was originally manufactured by Lycoming and overhauled in 2002 with components manufactured by Superior Air Parts, after which it was branded as a "Millennium Engine". At the time of the accident, the engine had accrued 1,135.6 flight hours since overhaul. AIRPORT INFORMATIONThe last maintenance event was for an annual inspection, on September 17, 2015, 7.1 flight hours before the accident. The airplane was powered by a normally aspirated, O-540-B4B5 engine. It was originally manufactured by Lycoming and overhauled in 2002 with components manufactured by Superior Air Parts, after which it was branded as a "Millennium Engine". At the time of the accident, the engine had accrued 1,135.6 flight hours since overhaul. ADDITIONAL INFORMATIONThe temperature and dew point values in the area at the time of the accident were not conducive to the formation of carburetor ice. TESTS AND RESEARCHEngine Monitor The airplane was equipped with a JP Instruments EDM-700 series engine monitor. The unit was configured to record the engine performance parameters including exhaust gas temperature (EGT), cylinder head temperature (CHT), and oil temperature. The recorded data was 34 minutes long, and initially revealed variations and rises in EGT and CHT consistent with taxi and takeoff. The EGT and CHT values then averaged about 1,275°F, and 325°F respectively, until 29 minutes after the recording began, when the EGT and CHT temperatures began to simultaneously drop. By the time the recording had stopped, the average CHT had reached about 225°F. During that period, the EGT dropped to 1,000°F, and then began an intermittent increase to about 1,225° lasting about 20 seconds, after which it dropped to the last recorded temperature of 200°F. The oil temperature remained at about 200°F throughout the flight. Engine Examination The airplane was recovered from the accident site and examined by the NTSB investigator-in-charge. A complete examination report is contained within the public docket, the following is a summary of the findings. The combination belly-mounted fuel selector/strainer was full of fuel; the fuel was tested with water-detecting paste, and no water was present. The fuel selector valve moved freely through all its positions, and the detents were well defined. A peripheral examination of the engine and fuel supply system did not reveal any anomalies. The engine sustained minimal damage during the accident sequence, most of the damage being sustained by the propeller, each blade of which was bent aft about midspan. All engine controls were continuous from their respective control arms through to the cabin controls and could be moved smoothly through their full range of travel. The inlet air filter and associated induction air lines, although damaged during impact, were free of obstruction, and the oil sump contained about 9 quarts of oil. The top spark plugs were removed and examined. They were massive-electrode types manufactured by Tempest, and their electrodes were mechanically intact, coated in black soot, and displayed normal wear signatures when compared with the Champion Spark Plugs AV-27 Check-A-Plug chart. The crankshaft turned freely when rotated by hand utilizing the propeller, and "thumb" compression was present on all cylinders. The propeller was removed and replaced with an undamaged unit, and an engine test run was performed utilizing fuel recovered from the airplane's fuel tanks after the accident. The engine started on the fourth cranking attempt and maintained a smooth idle of about 750 rpm. As the engine warmed up, the fuel and oil pressures remained within the green arcs of their respective gauges. Having reached operating temperature, a magneto check was performed, with a 75 rpm drop observed on each side. A propeller check was performed, and the engine speed dropped appropriately. The engine was then operated throughout its full speed range for an additional 10 minutes. Multiple throttle "chops", followed by rapid accelerations were initiated to simulate the accident scenario. The engine responded appropriately each time, with no hesitation or speed fluctuations. After engine shutdown, the top spark plugs were removed, and their electrodes now exhibited a grey coloration. The carburetor and engine driven fuel pump were then removed and examined. No anomalies were noted.