Accident Overview
On August 11, 2022, at approximately 2258 eastern daylight time, a Cessna 172N, registration N4751F, sustained substantial damage in an accident near Jamestown, New York. The flight instructor and the pilot receiving instruction were seriously injured. The airplane was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Flight Sequence
According to the flight instructor, the flight was a scheduled night cross-country from Lake County Executive Airport (LNN), Willoughby, Ohio, to Chautauqua County/Jamestown Airport (JHW), Jamestown, New York. The airplane was fully fueled before departure, and the instructor reported no issues during the flight to JHW. After performing a touch-and-go at JHW, the airplane began to climb. During the climb to cruise altitude, the engine started to "sputter." The pilot receiving instruction pitched the airplane for best glide speed and circled back toward JHW while attempting to restore engine power. He applied carburetor heat, but the engine did not regain power and seemed to be "at idle, just sputtering" with the propeller windmilling. Air traffic control advised the pilots of a private airstrip below their location. The flight instructor took control of the airplane to "spiral" down to the airstrip. The pilots were unable to locate the airstrip; consequently, the instructor "maintained best glide [speed] and went forward into the trees."
Damage and Examination
The airplane came to rest nose down at the base of a tree in the yard of a private residence. The fuselage, empennage, and both wings sustained substantial damage. Postaccident examination of the engine revealed that the single-drive dual magneto, which remained attached to the engine, would not produce a spark when the engine crankshaft was rotated. Internal examination of the magneto showed that when the magneto input drive was rotated, its drive cam lobe pushed the felt padding on both sides but neither set of contact points opened. A screwdriver was applied to the hold-down screws for the contact points, and they appeared to be torqued.
Maintenance Records
The maintenance logbooks contained no engine overhaul information or time-in-service information for the magneto. The operator believed the engine had been overhauled before purchasing the airplane in 2016, but they had no record of the overhaul. The airplane’s pre-purchase inspection entry on May 19, 2016, showed a tachometer time of 2,110.6 hours. At the time of the accident, the tachometer time was 4,020.3 hours. The logbooks had no entries indicating that 500-hour inspections had been completed on the magneto. The most recent magneto repair occurred on June 26, 2019, at a tachometer time of 2,893.8 hours. The maintenance entry read: "Removed magneto unit for timing issues; installed magneto and adjusted timing per engine manual."
Manufacturer Guidance
The Continental Ignition Systems Service Support Manual stated that magnetos should be inspected according to the "500 Hour Inspection" at the first 500 hours in service and every 500 hours thereafter. It also stated that ignition systems should be overhauled at the same time as the engine, and that magnetos and harnesses should be inspected for airworthiness at the expiration of four years, regardless of operating hours.
Weather Conditions
At 2256, the weather at JHW (about 7 miles northeast of the accident site) included a temperature of 60.8°F and a dew point of 53.6°F, with a calculated relative humidity of about 77.16%. Review of the icing probability chart in Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions at the time of the accident were conducive to "serious icing at glide and cruise power."