On October 8, 2015, at 1320 central daylight time, a Cessna 177RG, N1542H, experienced a loss of engine power during cruise flight after departure from Red Oak Municipal Airport (RDK), Red Oak, Iowa. The pilot performed a forced landing to a field during an attempted return to RDK. The airplane sustained substantial damage on impact with terrain during the forced landing. The private pilot and a passenger were uninjured. The airplane was registered to and operated by the pilot under 14 Code of Federal Regulations Part 91 as a personal flight that was not operating on an instrument rules flight plan that had been filed but not activated. Visual meteorological conditions prevailed at the time of the accident. The flight originated from RDK and was destined to Jonesboro Municipal Airport (JBR), Jonesboro, Arkansas. The pilot stated that after departing from RDK the airplane began to vibrate while climbing through 3,000 feet mean sea level (msl) for a filed cruise altitude of 7,000 feet msl. The pilot leveled the airplane at 3,000 feet msl and the indicated fuel flow was 12 gallons per hour (gph) when it should have been 16 gph. The fuel flow was "diminishing rapidly" so the pilot attempted to return to RDK but the airplane was losing altitude and had "minimal power" while flying at the airplane best glide speed. At 1,500 feet above ground level he lowered the landing gear, extended full flaps, and turned into the wind so as to land on a cut bean field that was below the airplane. The airplane touched down and then rolled into a corn field. Damage to the airplane included inward crushing of the right wing leading from mid-span, outward, and the left horizontal stabilizer leading edge. The airplane was powered by a Lycoming IO-360-A1B6D, serial number L-13859-51A, engine. Examination of the airplane by Federal Aviation Administration Inspectors from the Des Moines Flight Standards District Office revealed the number three engine cylinder intake pipe came loose and was completely missing bolts. Also, seven of the eight bolts holding number three cylinder on were broken loose. The number three engine cylinder intake bolts were unable to be located for examination. An engine logbook entry dated February 9, 2012, at a tachometer time of 3,070 hours and an engine time since major overhaul (SMOH) of 957.2 hours, stated, "…Replaced #3 intake gasket." The engine underwent its last annual inspection dated April 5, 2015, at a tachometer time of 3,377 hours and an engine time SMOH of 1,258.2 hours. The last engine logbook entry was dated August 19, 2015, at a tachometer time of 3,430.3 hours, for an engine oil and engine filter change. All of these maintenance entries were signed by the same airframe and powerplant mechanic.