On May 29, 2018, about 1958 eastern daylight time, a Hughes Aero Corporation Predator "C" powered parachute, N369SL, impacted trees and terrain during a forced landing following a takeoff from a private airstrip near Copemish, Michigan. The pilot and passenger sustained serious injuries. The powered parachute received minor damage during the impact sequence. The powered parachute was registered to and operated by a private individual as a Title 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed in the area about the time of the accident, and the flight was not operated on a flight plan. The local flight was originating airstrip at the time of the accident.According to the pilot, the wind was calm all day of the accident flight. The purpose of the flight was to demonstrate the powered parachute to a potential buyer. He called a local airport for recorded weather. The pilot arranged the powered parachute for a northwest departure from his property. He warmed up the engines and checked gauges. The pilot checked all lines and the condition of the parachute. The pilot explained the flight to the passenger, buckled him in, and put on his helmet. The pilot got in the pilot seat and put a helmet on. The pilot started the takeoff run. The pilot added that he has a landmark tree where he would abort a takeoff if he was not airborne by that point. However, on the accident flight he was about 8 ft above ground level at that point. The pilot realized that something was not right and that the powered parachute would not climb. The powered parachute was approaching 20 ft trees. The pilot attempted to land between a wire fence and the treeline. The powered parachute impacted the ground and a base of a tree. The pilot reported that there were no mechanical malfunctions during the flight and stated that the air was "heavier" than expected or the passenger was pulling down on the tail lines. Pulling on the tail lines can cause the parachute to "stall or land." At 1957, the recorded weather, about 17 nautical miles and 295 degrees from the accident site, at the Frankfort Dow Memorial Field, near Frankfort, Michigan, was wind calm; visibility 10 statute miles; sky condition clear; temperature 30° C; dew point 18° C; altimeter 29.87 inches of mercury. The field elevation at the airport was 634 ft above mean sea level and the calculated density altitude there was about 2,821 ft above mean sea level. A Federal Aviation Administration Inspector examined the wreckage and did not detect any preimpact anomalies that would have precluded operation of the powered parachute. The Inspector reviewed a 2015 aerial photograph of the pilot's property that showed a mowed 600-foot runway with a NW-SE orientation. At the time of the accident no runway could be detected on the property as the grass was 6 to 12 inches tall and appeared unused but for the accident flight.