What happened
On 11 November 2024, a PA28-161 Warrior III, registered PK-PBC, was conducting a mutual training flight near Tunggul Wulung, Indonesia. While performing VOR radial tracking exercises in the NANGUN training area, the aircraft experienced rough engine operation accompanied by flashing FADEC A and B warning lights.
Despite attempts by the pilot flying to reset the FADEC system and activate the FORCE B switch, the engine failed to return to normal operation. The crew observed a steady decline in RPM and engine load as the aircraft descended. Realizing the airport was unreachable, the student pilots declared a MAYDAY and selected the Cemara Sewu coastline for an emergency landing. To avoid bystanders, the crew adjusted their approach to an eastbound direction. The aircraft touched down on the coast, and while the pilots avoided heavy braking to protect the nose gear, the aircraft eventually came to a stop after the nose wheel sank into soft sand. There were no injuries.
The investigation
Investigators examined the engine at a manufacturer facility in Germany, performing bench tests with various FADEC and injector configurations. The testing revealed that the engine's power output was significantly restricted, reaching only approximately 71 kW instead of the required 99 kW.
Further analysis of the fuel system identified an internal malfunction within Injector No. 2. Electrical measurements showed a resistance of 0.2 Ohm, which is well below the manufacturer's specification of 0.4 to 0.5 Ohm. Detailed inspection of the injector revealed damage to a solenoid coil terminal pin and degradation of a sealing element, alongside evidence of localized thermal effects.
Findings
- An internal malfunction in Injector No. 2 caused abnormal electrical resistance, leading to insufficient fuel injection and reduced engine power.
- The engine ground run-up on the day of the flight was performed by the student pilots rather than a qualified engineer, as required by the school's procedures.
- The failure to have an engineer conduct the pre-flight ground run-up contributed to the inability to detect the technical anomaly before takeoff.