Incident Overview
A student pilot and flight instructor were conducting a simulated forced landing exercise. During the maneuver, the instructor reported that the engine failed to respond to throttle application after an extended period of power-off. The student pilot stated that he had used carburetor heat before and during the descent and had cleared the engine several times. The instructor subsequently executed a forced landing in a field.
Post-Landing Inspection
After the landing, a large streak of oil was observed running from the engine to the tail of the airplane. Examination revealed that the #3 cylinder oil drain line was disconnected. FAA inspectors found approximately 2 quarts of oil remaining in the engine crankcase.
Maintenance History and Findings
The #3 cylinder had been replaced prior to this flight. It was discovered that the rings on this cylinder were chrome, and the cylinder itself was chrome, which was contrary to the recommendations of the engine manufacturer. Additionally, the walls of the #3 cylinder were scorched.
Conclusion of Examination
The disconnected oil drain line and the use of chrome components against manufacturer guidelines were documented as part of the investigation. No other causal factors were identified in the source material.