N1249D

On September 11, 2024, at 1212 eastern daylight time, a Cessna 170A, N1249D, was substantially damaged when it was involved in an accident near Marshall, Indiana. The airline transport pilot received minor injuries. The airplane was operated under Title 14 Code of Federal Regulations Part 91 as a personal flight.

The pilot stated that during cruise flight at 3,500 ft above mean sea level and 120 mph, there was a loud repeating banging sound and a loss of engine power. Engine oil temperature increased to 220o F, engine oil pressure decreased below 35 psi, and engine oil sprayed onto the airplane’s windshield. As the airplane descended, the pilot looked for an area to perform a forced landing. The pilot planned to land the airplane on a short open area but overshot the open area because he could not dissipate enough of the airplane’s energy. He then landed the airplane on a corn field where it contacted the corn, nosed over, and impacted the ground. The airplane sustained substantial damage that included damage to the wings, vertical stabilizer, and rudder.

Postaccident examination of the engine revealed a hole in the crankcase above the No. 6 cylinder assembly. The No. 6 connecting rod was fractured near its base.

Metallurgical examination of the No. 6 connecting rod revealed fracture features that were consistent with fatigue cracking. The cracks initiated at multiple locations on the outer surface opposite the inner bearing surfaces that mated the crankshaft. These cracks propagated through most of the rod yoke arm cross section until the remainder subsequently fractured from tensile overstress. All other fracture surfaces were consistent with overstress fracture.

Maintenance records showed the engine received a major overhaul on September 27, 2010. The last annual inspection on the engine was dated March 1, 2024, and the engine had 572.7 hours since the major overhaul. Continental manual M-O Ch. 6-3, Table 6-1 states, C125, C145 series and O-300-A,B,C,D engines have a time between overhauls of 1,800.0 hours or 12 years, whichever comes first.