Pilot Described That The Engine “Shuddered” Before Smoke Began Emanating From The Engine Area And Entered The Cockpit

Location: Wetumpka, Alabama Accident Number: ERA23LA331
Date & Time: August 10, 2023, 19:20 Local Registration: N7117M
Aircraft: Cessna 175 Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial) Injuries: 1 None
Flight Conducted Under: Part 91: General aviation - Personal

Analysis: While enroute to the destination airport the pilot described that the engine “shuddered” before smoke began emanating from the engine area and entered the cockpit. The pilot then attempted to land at a diversionary airport and during the diversion described that the engine intermittently lost power and he observed sparks and flames emanating from it. Upon reaching the midpoint of the diversionary runway, the airplane was flying at too fast of an airspeed to land, so the pilot performed a go-around, during which the engine lost power and the propeller stopped rotating completely. The airplane subsequently struck trees and was substantially
damaged. 

Postaccident examination of the wreckage revealed that the engine’s crankcase was breached in the vicinity of the No. 3 cylinder. A deformed connecting rod was recovered, but the connecting rod's end cap was not. The crankshaft journal exhibited heavy mechanical damage. An unquantified amount of oil residue was found in the engine cowling and on the airframe. The wreckage was subsequently sold for salvage and a further detailed examination of the engine could not be completed. Based on this information, the loss of engine power was likely the result of the separation of the No. 3 connecting rod from the crankshaft.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- A total loss of engine power due to the separation of the No. 3 connecting rod from the crankshaft. 

FMI: www.ntsb.gov