On October 17, 2015, about 1200 central daylight time, a Bobby Martin, AutoGyro MTO Sport gyroplane, N3232Z, impacted terrain in a remote swampy area near Wallisville, Texas. The pilot was not injured, and the gyroplane was substantially damaged. The gyroplane was registered to and operated by a private individual, as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions (VMC) prevailed and a flight plan had not been filed. The gyroplane had departed Chambers County Airport (T00) Anhuac, Texas, about 1130 for a local flight.The pilot took off to go sightseeing for about 30 to 45 minutes to look at the wetlands. He reported being about 250 to 300 ft. above the ground in straight and level flight when he heard and felt something break loose behind him, near where the engine is located. The gyroplane then developed a severe vibration. The pilot reduced power which reduced the vibration but resulted in the gyroplane descending. He added power again, but the gyroplane vibrated severely and wasn't regaining performance. Seeing that he would not make it back to a suitable landing location, the pilot selected a clear area in the swamp beneath him to land. During the forced landing, the gyroplane's right main landing gear sank into the swamp and the gyroplane rolled over onto its right side causing substantial damage to the main rotor blades and rotor mast. A postaccident examination of the pusher propeller showed that one of the three carbon fiber blades had split and come apart. Further examination of the propeller blade showed one half of the blade missing for 3/4 of the outboard length, about 1.5 in. missing from the blade tip of the half that remained, two deep cuts in the leading edge, and a fracture at the blade root near the hub. The damage was consistent with an impact to the blade, however, no object that could have caused such damage was located. Per the aircraft manufacturer, the propeller blade was constructed as two separate halves, bonded together prior to curing, with a foam filled core that bonded to the resin. The manufacturer was aware of two similar cases where a blade split open. Both involved where seat cushions came out of the aircraft and struck the propeller. No other preaccident anomalies with the gyroplane were found.