What happened
On December 20, 2024, a Tecnam P92E MKII, registration LV-S130, was conducting a general aviation ferry flight from Aeródromo Rivadavia/Aerotec in Mendoza to Aeródromo Cruz Alta in Córdoba. During the cruise phase of the flight, the pilot detected the smell of burning oil and observed a simultaneous drop in oil pressure readings.
Following established standard operating procedures, the pilot identified the nearest suitable airfield, notified air traffic control, and declared an emergency. The pilot successfully executed an emergency landing at Aeródromo Mercedes in the province of San Luis without further incident. There were no injuries and no damage to the aircraft.
The investigation
Following the incident, maintenance personnel from Air Andes SRL conducted an inspection of the engine at the aircraft's location. The investigation focused on the engine powerplant to identify the source of the oil leak. The technical team performed a cleaning of the aircraft, drained the oil system, and inspected the oil filter and magnetic particle detector. Additionally, a borescope inspection was conducted, and the crankshaft rotation resistance was measured.
Findings
Technical analysis revealed that the loss of oil pressure was caused by the absence of an M8x20 Allen screw and its associated sealing ring. The investigation established that the screw had not been properly tightened during its previous installation. Due to engine vibrations during flight, the screw progressively loosened and eventually detached from the engine. This failure allowed pressurized oil to leak from the engine, leading to the observed drop in pressure and the smell of burning oil.