What happened
On 13 April 2010, a Cathay Pacific Airways Airbus A330-342, registration B-HLL, was performing a scheduled flight from Surabaya to Hong Kong International Airport. During the cruise phase, the crew received an engine control system fault message indicating a jammed fuel metering valve on the number two engine. As the aircraft transitioned into the descent phase, the situation escalated when the number two engine experienced a surge and subsequent stall.
Shortly after, the number one engine also experienced a surge and stall. The crew attempted to manage the engine failures, which included a loss of thrust control and an electrical transient following a power supply interrupt. Due to the instability of the engines, the crew eventually shut down the number two engine in flight. The aircraft landed at Hong Kong International Airport, and an evacuation was initiated.
The investigation
The investigation focused on the mechanical failures of the Rolls-Royce Trent 700 engines and the integrity of the fuel supply. Investigators examined the flight data recorders, cockpit voice recorders, and engine components. A critical part of the inquiry involved analyzing the fuel hydrant refuelling system at the West Apron (WARR) of Hong Kong International Airport.
Technical analysis of the engine's fuel metering valves (FMV) and variable stator vanes (VSV) revealed that the components were being impeded. Laboratory testing of fuel samples and filter monitors identified the presence of SAP (Super Absorbent Polymer) spheres within the fuel system. These spheres, which are used in fuel-water separator elements, had migrated into the aircraft's fuel supply.
Findings
- The primary cause of the engine surges and stalls was contamination of the aircraft fuel by SAP spheres from the airport's hydrant refuelling system.
- These microscopic polymer spheres caused the fuel metering valves and variable stator vanes to jam or become unresponsive, leading to a loss of thrust control.
- The contamination originated from the fuel-water separator elements used in the hydrant refuelling circuit at the airport.
- The investigation also noted that the engine's ability to maintain stable operation was compromised by the physical presence of these particulates in the high-pressure fuel components.