N4751FCessna 172N · 1979

On August 11, 2022, about 2258 eastern daylight time, a Cessna 172N, N4751F, was substantially damaged when it was involved in an accident near Jamestown, New York. The flight instructor and pilot receiving instruction were seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

According to the flight instructor, the flight was scheduled as a night cross-country flight 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 noted no issues during the flight to JHW. During the climb to cruise altitude after the touch-and-go procedure at JHW, the engine began to “sputter.” The pilot receiving instruction pitched the airplane for the 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 the airplane’s location, and the flight instructor took control of the airplane to “spiral” down to the airstrip. The pilots were unable to locate the airstrip; as a result, the instructor “maintained best glide [speed] and went forward into the trees.”

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 revealed that, when the magneto input drive was rotated, its drive cam lobe pushed the felt padding on both sides but that 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.

The maintenance logbooks showed no engine overhaul information or time-in-service information for the magneto. The operator thought that the engine had been overhauled before purchasing the airplane in 2016; however, 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 contained 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.”

The Continental Ignition Systems Service Support Manual stated the following:

Inspect all magnetos according to the “500 Hour Inspection” in Section 6-2.3, at the first 500 hours in service and every 500 hours thereafter. If the magneto has more than 500 hours, inspection as outlined above must take place within the next 100 hours, or at the next scheduled inspection period, whichever occurs first, and at 500-hour intervals thereafter. Make an appropriate logbook entry signifying compliance with this paragraph and referencing the magneto serial numbers involved after completing the inspections.

Ignition systems are subject to the same environmental conditions and wear as the engine. Therefore, overhaul the magnetos and replace the ignition harnesses at the same time as the engine. Engine overspeed, sudden stoppage or other unusual circumstances may require engine overhaul prior to engine manufacturer's recommendations. In such circumstances overhaul the magneto, regardless of “in service time”, with particular attention focused on rotating parts, bearings and electrical components.

Inspect magnetos and harnesses for airworthiness at the expiration of four years, without regard to the accumulated operating hours since new or last overhaul.

At 2256, the weather reported at JHW, which was about 7 miles northeast of the accident site, included a temperature of 60.8° F and a dew point of 53.6° F. The calculated relative humidity at this temperature and dewpoint was about 77.16%. Review of the icing probability chart contained within Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 revealed the atmospheric conditions at the time of the accident were conducive to “serious icing at glide and cruise power.”