Incident Overview
On 21 September 2018, at 14:30 LMT, a pilot and passenger departed from EPBC airport in an AT-3 R100 aircraft (registration SP-PPL) equipped with a Rotax 912 iS engine. The flight was part of the pilot's build-up of flight time for a command qualification.
Sequence of Events
During climb at 900 feet, the engine warning lights for Line A and Line B illuminated, indicating exceedance of permissible engine parameters. Simultaneously, the pilot observed a large amount of coolant fluid escaping from the engine compartment. The pilot immediately declared an engine failure, returned to the airport, and landed on runway 28.
After the warning lights activated, the pilot focused on landing procedures and did not monitor the engine parameters displayed on the EMU (Engine Monitoring Unit) indicator.
Investigation Findings
Reading of the EMU memory card revealed that during the flight, oil temperature and cylinder head temperature were in the warning (yellow) range for 7 minutes 28 seconds and 9 minutes 28 seconds, respectively. Additionally, these parameters exceeded the maximum (red) range for oil temperature for 2 minutes 28 seconds and for cylinder head temperature for 8 minutes.
The pilot had logged six hours on AT-3 aircraft but this was his first flight with the EMU indicator. He did not familiarize himself with the operation and handling of the engine parameter monitoring system before the flight, and consequently could not utilize the EMU indicator, which could display the relevant parameters corresponding to the exceedances shown on the indicator.
It was established that the pilot conducted the flight with the air inlet shutters closed. According to the Flight Manual Supplement No. 65, the air inlet shutter for the radiators and the oil cooler shutter should be opened before takeoff after the engine oil temperature reaches 50°C. The meteorological conditions on the day of the incident did not require the shutters to be closed before takeoff.
The closed air inlet shutters caused the cylinder head and oil temperatures to rise to unacceptable values. This situation could have been prevented if the pilot, after the warnings appeared, had read the engine parameters and immediately opened the air inlet shutters, reduced power, and, if possible, initiated a rapid descent.
Due to the exceedance of the maximum permissible cylinder head and oil temperatures, the engine was sent to a maintenance facility for an inspection. No damage was found, and the engine was cleared for further operation.
Probable Cause
The incident was caused by a takeoff with closed air inlet shutters. A contributing factor was the pilot's unfamiliarity with the operation and handling of the engine parameter monitoring system.