On 27 March 2024, a Sichuan Airlines Airbus A320 operating flight 3U8471 from Chengdu to Harbin experienced a failure of Generator No. 2 during the initial descent into Harbin. During the subsequent attempt to start the auxiliary power unit (APU), Generator No. 1 also disconnected, causing the aircraft to briefly transition into an emergency electrical configuration. Once the APU start was successfully completed, Generator No. 1 was reset, the aircraft exited the emergency configuration, and the flight continued to a safe landing at Harbin Airport with no injuries or damage.
The investigation determined that the direct cause of the event was the failure of Generator No. 2, which was traced to the burning of its excitation coil during the descent. At the same time, the process of starting the APU increased the electrical load on Generator No. 1. It was found that Generator No. 1 had an excitation rotor coil resistance that exceeded allowable limits, which led to unstable behaviour, including significant fluctuations in excitation current and output voltage. These irregularities activated the system’s protective mechanisms, resulting in the automatic disconnection of Generator No. 1 and the temporary loss of normal electrical power, placing the aircraft in an emergency configuration.
In its conclusion, the investigation classified the occurrence as a serious incident of mechanical origin in accordance with civil aviation occurrence classification criteria. This classification was based on the presence of multiple system failures that significantly affected aircraft operation and the temporary reliance on backup or emergency electrical power for continued safe flight.
As a result of the findings, several safety recommendations were issued to the operator. These included conducting further technical analysis in cooperation with the aircraft manufacturer to establish the underlying root causes of the generator failure, as well as reviewing and strengthening procedures for managing generator-related emergencies. The operator was also advised to improve dispatch standards by more strictly limiting deferred defects associated with generators, and to enhance condition monitoring practices. Additional recommendations focused on improving maintenance intervals, troubleshooting methods, and overall reliability monitoring. The investigation further emphasised the importance of analysing removed components and maintenance findings and suggested the use of Quick Access Recorder (QAR) data to support early detection of generator performance degradation, again in coordination with the manufacturer.