On October 6, 2017, about 1415 eastern daylight time, an Ercoupe 415-C, N3538H, experienced a partial loss of engine power after takeoff and was substantially damaged during the subsequent forced landing near Penns Cave Airport (N74), Centre Hall, Pennsylvania. The private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight which was conducted under the provisions of 14 Code of Federal Regulations Part 91.The pilot reported that the airplane had climbed to 200 ft above ground level after takeoff from N74 when it experienced an "appreciable" loss of engine power, the flight controls became "sluggish," and the airplane would no longer climb. He noted the engine was operating about 2,000 rpm, which was 275 rpm below the nominal full-power setting of 2,275 rpm at takeoff. The pilot elected to perform a forced landing to a field directly off the departure end of the runway. During the landing roll, the airplane struck fences which resulted in substantial damage to both wings. The pilot held a private pilot certificate with a rating for airplane single engine land. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued December 30, 2015. The pilot reported 276 total hours of flight experience, 121 hours of which were in the Ercoupe. According to FAA records, the airplane was manufactured in 1946, and was powered by a Continental C75-12F 75-horsepower, 4-cylinder engine. Its most recent annual inspection was completed November 12, 2016 at 1,712.8 total aircraft hours. Examination of available maintenance records revealed that the first entry in the engine logbook was dated October 22, 2001 at the completion of an annual inspection. The entry reflected 34.6 hours since major overhaul. At its most recent annual inspection, the entry reflected 147.6 hours since major overhaul. The engine accrued 113 hours between October 2001 to November 2016. The hourly interval between each annual inspection was about 10 hours. At 1253, the weather recorded at University Park Airport (UNV), State College, Pennsylvania, 11 miles west of N74 included an overcast ceiling at 2,400 ft and wind from 190° at 5 knots. The temperature was 20°C, and the dew point was 17°C. The altimeter setting was 30.12 inches of mercury. The wreckage was examined at the accident site by a Federal Aviation Administration inspector, and all major components were accounted for at the scene. Both wings were substantially damaged. The left, right, and fuselage fuel tanks were intact and contained fuel. Flight control, engine control, and fuel system continuity were confirmed. The engine crankshaft was rotated by hand at the propeller and compression was confirmed on all cylinders but the No. 2 cylinder using the thumb method. Removal of the No. 2 cylinder valve cover revealed the No. 2 exhaust valve in the open (compressed) position without rocker-arm contact. The valve remained in the open position through several rotations of the crankshaft. According to the Continental Engines, Maintenance Manual, Standard Practice for Spark Ignited Engines, the recommended overhaul interval for C75-series engines was every 1,800 hours or every 12 years.