What happened
On Wednesday, April 19, 2000, at approximately 09:15, a Cessna 177 RG (registration F-BVIG) was conducting a local flight near Cannes-Mandelieu. After performing a ten-minute run-up at the edge of the runway, the pilot departed at 09:55. Approximately twenty minutes into the flight, while cruising at 2,000 feet, the pilot observed the propeller moving to the full fine pitch position. This was immediately followed by intense vibrations and an audible detonation from the engine. As oil pressure dropped, the engine ceased functioning entirely.
In response to the engine failure, the pilot initiated an emergency landing in a nearby field near Tanneron. During the landing roll, the nose gear struck an uneven section of a dirt path, causing the gear to separate from the airframe. The propeller subsequently struck the ground, causing the aircraft to nose over and come to rest on its back. The aircraft was destroyed during the impact.
The investigation
The investigation focused on the internal components of the Lycoming IO-360-A1B6B engine. Physical examination of the engine revealed two fractures on the upper portion of the left crankcase half. These perforations allowed investigators to observe that the head of connecting rod No. 2 had broken and become detached from the crankshaft.
Further disassembly and internal inspection showed that the bearing caps for connecting rods No. 2 and No. 4 had failed following excessive wear and overheating of the bearings. Additionally, the bearing for connecting rod No. 3 showed significant degradation and signs of overheating.
Investigators also reviewed the engine's maintenance history. The engine had undergone a complete overhaul and component replacement, including new connecting rod bolt heads, in late 1998. Following this maintenance, the engine was stored for seventeen months before being reinstalled in the aircraft. No evidence of corrosion was found during the inspection.