Accident
On September 11, 2024, at 1212 eastern daylight time, a Cessna 170A, registration N1249D, was substantially damaged when it impacted terrain near Marshall, Indiana. The airline transport pilot, who was the sole occupant, received minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The pilot reported that during cruise flight at 3,500 ft above mean sea level and 120 mph, a loud repeating banging sound was heard, followed by a loss of engine power. Engine oil temperature increased to 220°F, oil pressure decreased below 35 psi, and oil sprayed onto the windshield. As the airplane descended, the pilot searched for a suitable forced landing area. He intended to land on a short open area but overshot it due to inability to dissipate enough energy. The airplane subsequently touched down in a corn field, contacted the corn, nosed over, and struck the ground. The impact resulted in substantial damage to the wings, vertical stabilizer, and rudder.
Aircraft and Pilot
The airplane was a Cessna 170A. The pilot held an airline transport pilot certificate. No further information about the pilot is available from the source.
Engine Examination
Postaccident examination revealed a hole in the crankcase above the No. 6 cylinder assembly. The No. 6 connecting rod was fractured near its base. Metallurgical analysis of the No. 6 connecting rod indicated fracture features consistent with fatigue cracking. Cracks initiated at multiple locations on the outer surface opposite the inner bearing surfaces that mate with the crankshaft. These cracks propagated through most of the rod yoke arm cross section until the remaining material fractured from tensile overstress. All other fracture surfaces appeared consistent with overstress fracture.
Maintenance Records
Maintenance records showed that the engine received a major overhaul on September 27, 2010. The last annual inspection was dated March 1, 2024, at which time the engine had accumulated 572.7 hours since the major overhaul. The Continental manual (M-O Ch. 6-3, Table 6-1) specifies that C125, C145 series and O-300-A,B,C,D engines have a time between overhauls of 1,800 hours or 12 years, whichever comes first.