On February 17, 2009, approximately 1630 central standard time, a Cessna 150L single-engine airplane, N747KA, experienced a partial loss of engine power while maneuvering near Grayslake, Illinois. The airplane was not damaged. The airline transport pilot and passenger were not injured. The airplane was operated by Palwaukee Flyers and registered to Flight Center at Service Aviation, Inc., Wheeling, Illinois. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The local flight departed Chicago Executive Airport (PWK), Wheeling, Illinois, at 1610. According to the local authorities and the pilot, the pilot rented the airplane from Palwaukee Flyers at PWK. While maneuvering near Grayslake, the airplane experienced a partial loss of engine power and the pilot could not maintain altitude. The pilot elected to perform a precautionary landing to a frozen lake. The airplane landed uneventfully on the frozen lake. The operator stated that the Continental O-200A48 engine experienced a problem with the number one cylinder. The airplane was recovered for further examination. A review of the engine logbooks revealed that the engine underwent its most recent 100-hour inspection on February 6, 2009, at a tachometer time of 9,584.1 hours. At the time of the incident, the engine had accumulated 3,429.2 hours since major overhaul. Teledyne Continental Service Information Letter SIL98-9 listed the time between overhaul for the O-200A engine, of 1,800 hours, or 12 years. Teledyne Continental Motors records revealed the engine was remanufactured at the factory in 1993. Because Palwaukee Flyers operates under Part 91, they were not subject to the Federal regulations that require compliance with manufacturers' recommended maintenance instructions. Examination of the engine by an engine repair facility revealed that the number 1 cylinder intake valve fractured. The cause of the failure could not be determined. The following incident was reported to another NTSB investigator during an investigation of another accident with the operator. This incident was not reported to the Federal Aviation Administration and/or the NTSB. On August 11, 2008, a student pilot and a flight instructor reportedly experienced the effects of carbon monoxide poisoning during an instructional flight in N747KA. An engine logbook record for N747KA, dated August 14, 2008, showed that the left front exhaust stack riser was removed and replaced at a tachometer time of 9,457.8 hours.