Incident Overview
A student pilot was practicing multiple touch-and-go landings when she observed a partial loss of engine power. According to her account, after turning onto a downwind leg, she heard an unusual sound from the engine and it appeared to lose power. She subsequently initiated an approach for an off-airport landing. During the final approach, the aircraft struck power lines and then nosed over into the ground.
Engine Examination
After the event, an examination of the engine was conducted. No mechanical discrepancies were found, except for the presence of lead deposits on the spark plugs. However, the spark plugs were tested and functioned satisfactorily.
Weather Conditions
At the time of the incident, weather conditions were conducive to the formation of induction icing. This was noted for both rated power and glide power settings.
Conclusion
The investigation did not determine a specific cause for the partial power loss. The engine appeared to operate normally after the event aside from the lead deposits, and the weather conditions were favorable for induction icing, which could affect engine performance under certain conditions.