Aircraft: Cessna 177RG. Injuries: None. Location: Gila Bend, Ariz. Aircraft damage: Substantial.
What reportedly happened: According to the pilot, while the airplane was in cruise flight he heard a loud noise from the engine compartment, followed by an immediate loss of engine power.
He attempted to restart the engine while diverting to the nearest airport. The engine would not restart and he realized that he wouldn’t be able to reach the airport, so he decided to land on an interstate highway. As he approached the highway, the pilot noticed heavy traffic and decided to land on an adjacent service road. During the landing roll, the left wing hit a tree.
The post-accident examination of the engine revealed that both sets of magneto points were not opening. Inspection of the single-drive dual magneto found that the cam followers on both sets of points were worn to the point that they could no longer open the contacts.
The magneto had accumulated 603.7 hours at the time of the accident since installation and 92.56 hours since the most recent magneto timing adjustment. No further anomalies were noted during the examination of the engine that would have precluded normal operation.
Probable cause: A total loss of engine power during cruise flight due to both sets of magneto points failing to open as a result of excessive wear of the magneto cam followers.
NTSB Identification: WPR11FA186
This April 2011 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.