Synopsis
At 1216 hours on 20 July 2021, a United Parcel Service Company (UPS) Boeing 747-8 freighter, registration N624UP, departed from Hong Kong International Airport (VHHH) for Dubai International Airport (OMDB) as flight UPS3. About four minutes after takeoff, the flight crew shut down the left outboard (No. 1) engine due to excessive engine speed. The crew elected to return to Hong Kong. After landing on Runway 07L, the No. 1 engine caught fire during water application by the airport fire contingent (AFC). There was no other damage to the aircraft apart from thermal damage to the engine. No one was injured.
Investigation Findings
Following the incident, the Air Accident Investigation Authority (AAIA) of Hong Kong conducted an inspection of the No. 1 engine. The engine was then removed and sent to the manufacturer, General Electric (GE), for further examination under the supervision of the National Transportation Safety Board (NTSB) of the United States. The examination identified a fuel leak from the supply pressure (P1) bypass valve port fitting on the fuel metering unit (FMU). Subsequent inspection revealed that the fitting was finger loose with a gap between the fitting and the housing. The packing of the fitting was also found damaged.
The investigation determined that the serious incident was caused by improper installation of the P1 bypass valve port fitting on the fuel metering unit, which resulted in a fuel leak that led to the engine fire. The investigation team issued two safety recommendations.
Conclusion
The probable cause of the serious incident was the improper installation of the P1 bypass valve port fitting on the fuel metering unit, causing a fuel leak that rendered the engine fire.