What happened
On 26 April 2024, a Diamond DA42NG with registration N566CB was conducting a scheduled test flight at Sultan Abdul Aziz Shah Airport, Subang. The flight was intended to verify recent maintenance work performed on the aircraft's cooling system. Shortly after departing from Runway 15, the pilot observed a high coolant temperature reading in the red zone on the No. 2 engine, accompanied by rough engine operation.
In response to the malfunction, the pilot shut down the affected engine and declared a Mayday to the Sub and requested an immediate return to base. The aircraft was redirected to Runway 33. However, during the approach and landing phase, the pilot failed to extend the landing gear. This resulted in a belly landing on the runway, where the aircraft skidded approximately 220 metres. While there were no fatalities, the aircraft sustained significant damage to both propellers and the engine cowlings.
The investigation
AAIB Malaysia examined the mechanical, human, and regulatory aspects of the incident. Investigators reviewed engine datalog information, which confirmed that the coolant temperature had exceeded approved limits. The investigation also looked into the pilot's adherence to Standard Operating Procedures (SOPs) and the accessibility of emergency resources.
Technicians analyzed the damage to the airframe, noting severe impact marks on the propellers and the tail boom. The investigation also addressed the operational context, noting that the pilot was managing the emergency while relying on an iPad for checklist access, which contributed to the high workload during the critical landing phase.