Incident Overview
On May 26, 2019, a Cessna 152 aircraft operated by a student pilot holding a PPL(A) license experienced multiple system anomalies during a scheduled training flight near Opatów, Poland. The flight departed at 11:30 UTC for a route training exercise. The aircraft landed without further incident at 13:30 UTC.
Flight Details
While cruising at 3,000 feet near Opatów, the pilot noticed that the fuel gauges were indicating significantly less fuel than expected. The pilot discontinued the cross-country flight to EPCD and diverted toward Stalowa Wola airport (EPST). During the approach to EPST, the pilot observed erroneous oil temperature indications and a message on the Garmin G 500 and radio display stating "External power lost." The pilot did not notice the ammeter showing battery discharge or the low-voltage warning light. After landing, a mechanic confirmed that the battery was fully discharged.
Findings
The investigation determined that the incident occurred because the alternator switch (ALT) was not turned on for the flight. Prior to taxiing onto the runway, the pilot had performed a procedure to check alternator operation, which involved turning the alternator off and on, but subsequently failed to leave the switch in the ON position. The battery was replaced, and a ground run-up verified normal alternator and electrical system function, including fuel gauges, oil temperature, and avionics.
Preventive Actions
The operator, after reviewing similar occurrences at its ATO in Chełm, decided to remove from the Standard Operating Procedures (SOPs) the step that required checking alternator operation by cycling the switch before taxiing. The aircraft battery was replaced and the system tested satisfactorily.