Incident Details
On 1 February 2020, an Aero AT-3 R100 (registration SP-PPL) was conducting training flights at EPBC. The crew consisted of a student pilot and an instructor. They had been flying in the airport traffic zone for approximately 30 minutes before returning to perform circuit patterns.
Sequence of Events
After the fourth circuit, at an altitude of about 1000 feet, the instructor heard a concerning noise resembling a bang from the vicinity of the engine. Shortly thereafter, the crew noticed light smoke in the cockpit and detected a smell of burning insulation. The instructor observed a red warning light for "Line A" and promptly took control from the student. Following the aircraft's operating manual, the instructor switched off "Line A" and executed a right turn to land. The landing on Runway 10 was completed without further incident.
Cause
The investigation determined that contamination of the EGT-2 (exhaust gas temperature) connector and the fuel gauge connector was the cause of the incident.
Corrective Actions
The aircraft operator cleaned the contacts of the EGT-2 connector and the fuel gauge connector. No contributing factors or additional safety recommendations were identified.