What happened
On May 14, 2020, a Diamond DA20-C1, registration SP-NLN, was performing a cross-country flight near Kutno when the pilot observed an abnormal increase in oil pressure. While the oil temperature remained within normal parameters, the pressure rose to levels between 70 and 85 psi, exceeding the standard operating range of 30 to 60 psi.
Upon detecting this deviation, the pilot notified FIS Warsaw and decided to terminate the mission. The pilot diverted the aircraft to an airfield in Nowe Miasto, where a safe landing was completed without further incident or damage to the aircraft.
The investigation
The investigation focused on the engine's thermal management during the flight. Investigators noted that the ambient temperature at takeoff was 11°C, and it remained low at 13° and during the flight. The investigation examined the pre-flight procedures and the use of engine cooling inlet covers.
Findings
Findings revealed that the pilot failed to install engine cooling inlet covers during pre-flight preparations. According to the aircraft's Flight Manual, these covers should be used when temperatures are below 12.5°C. Because the covers were not installed, the engine oil did not reach the proper operating temperature, resulting in increased oil density and the subsequent rise in oil pressure.
Safety action
Following the incident, the operator conducted a detailed review of the event with flight instructors and both civilian and military students. Flight personnel were reminded of the necessity of performing thorough pre-flight inspections and were specifically instructed to analyze ambient temperatures and expected daily temperature trends before flight operations.