What happened
During a return leg of a navigation flight between Etampes and Chartres, the crew of a Robin DR 315.M, registration F-BSBG, experienced a sudden drop in oil pressure. The instructor noted that the oil pressure warning light illuminated, though engine temperature remained stable. Given the prevailing weather conditions—including a 15 to 20 knot wind and an overcast ceiling at 600 feet—the instructor elected to divert to Etampes aerodrome while simultaneously scouting for a suitable emergency landing site.
Approximately two and a half minutes after the initial warning, the engine began to vibrate heavily before suffering a complete failure. The instructor attempted to feather the propeller to a horizontal position but was unsuccessful. The aircraft subsequently performed an emergency landing in a field. There were no fatalities among the three occupants, though the aircraft sustained damage to the propeller, engine, and engine cowling.
The investigation
The investigation focused on the mechanical failure of the Lycoming 0-235 C 2 A engine. Investigators examined the oil system and identified a leak occurring at the crimping point of the oil pressure sensor. This leak resulted in a critical loss of oil within the system.
Findings
- The primary cause of the engine failure was a lack of lubrication caused by an oil leak.
- The leak originated at the crimping of the oil pressure probe.
- The loss of oil led to the internal seizure of the engine.