Accident Overview
On June 18, 2011, at approximately 1635 central daylight time, a Cessna 172N (registration N172NT) sustained substantial damage when it nosed over during a forced landing following a loss of engine power. The incident occurred about 2 miles southwest of Midway Airport (MDW) in Chicago, Illinois. The pilot and three passengers were not injured.
Flight Details
The aircraft was registered to Woma LLC and operated by Aviation Professionals Inc. under 14 Code of Federal Regulations Part 91 as a training and rental airplane. Visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local personal flight had originated from Lansing Municipal Airport (IGQ) in Lansing, Illinois, about 1610.
Pilot Report
The pilot reported that about 5 miles from MDW, the engine began to run rough, and approximately 20 seconds later, it lost power. Attempts to restore engine power were unsuccessful. The pilot executed a forced landing to a field; however, the airplane nosed over during the landing rollout due to the soft terrain. The field was used as a water retention reservoir with 2-foot-tall grass and approximately 4 inches of water and mud.
Postaccident Examination
A postaccident examination revealed that the #3 cylinder exhaust valve push rod had buckled and fractured near mid-length. The fracture surface was uniform in appearance and oriented approximately 45 degrees to the surface of the push rod, consistent with an overload failure. At the time of the examination, the exhaust valve was free to move, but the damage to the push rod was consistent with a stuck valve condition during operation. No other engine anomalies were observed.
Engine and Maintenance
The accident airplane was powered by a 160-horsepower Lycoming O-320-H2AD engine (serial number L-80290-76T). Maintenance records indicated that the most recent annual inspection was completed on May 10, 2011. The engine had accumulated about 1,567 hours since overhaul, with approximately 67 hours since the annual inspection.