HB-IQZ

HISTORY OF FLIGHT

On October 5, 2003, about 0155 eastern daylight time, an Edelweiss Airbus 330-243, HB-IQZ, experienced an engine fire and an uncontained engine failure of the No. 1 engine while climbing through flight level (FL) 230. The flight crew contacted Miami Center and requested clearance to return to Miami International Airport (MIA) Miami, Florida. The flight had departed MIA about 0145 on a regularly scheduled flight to Zurich, Switzerland, and was operating on an instrument flight rules flight plan under the provisions of 14 Code of Federal Regulations (CFR) Part 129. No injuries were reported for the 12 crewmembers and 171 passengers on board. Visual meteorological conditions prevailed at the time of the incident.

During interviews after the incident, the flight crewmembers reported that as they were climbing through FL 230, the master warning system annunciated along with a corresponding electronic centralized aircraft monitoring (ECAM) system message indicating turbine exhaust gas temperature overheat in the No. 1 engine. They reported that, shortly afterward, they felt heavy vibrations in the airplane and the No. 1 engine's fire warning system activated with a corresponding ECAM fire warning message. The pilots reported that they discharged one fire bottle into the nacelle but that the fire warning lights did not extinguish. They stated that a second fire bottle was discharged but that the fire warning lights remained illuminated. They indicated that an extra flight crewmember went back to the passenger cabin to see if he could inspect the engine from the passenger windows. The flight crewmember was unable to see any fire at that time but passengers reported that they had seen sparks, then white and orange flames.

The flight crew contacted Miami Center and requested clearance back to MIA. During the descent to MIA, at about 300 knots, the No. 1 engine fire warning lights extinguished. The pilot-flying requested a fire brigade to stand by for the landing, which the flight crew successfully performed with only the No. 2 engine operational. The fire brigade gave the go-ahead for the airplane to taxi up to gate E33. The flight crew had the airplane down safely on the ground within 20 minutes of the No. 1 engine failure. During the interviews held after the event, the pilot-flying stated that the air and ground traffic control communications were "great" and that the flight crew used crew resource management (CRM) effectively.

ENGINE INFORMATION

Both engines were Rolls-Royce Trent 772-60/16 turbofan engines and were installed on the airplane when it was delivered new from Airbus on November 21, 2000; neither engine had been removed or overhauled since they were installed. Both engines had accumulated 15,169 hours time since new (TSN) and 2,348 cycles since new (CSN).

The Rolls-Royce Trent 700 engine is a three-shaft, high-bypass-ratio, modular turbofan engine with low pressure (LP), intermediate pressure (IP) and high pressure (HP) compressors driven respectively by LP, IP, and HP turbines through coaxial shafts. The LP system consists of a single-stage, wide-chord, hollow fan blade compressor driven by a four-stage turbine. The IP system consists of an eight-stage axial flow compressor driven by a single-stage turbine. The HP system consists of a six-stage axial flow compressor driven by a single-stage turbine. The combustion system is an annular construction incorporating fuel spray nozzles.

The initial on-scene examination of the No. 1 engine revealed that the IP turbine case exhibited a 360° circumferential rupture that created a gap between the IP and LP turbine cases. The IP turbine disk was still in place, but the disk rear drive arm was fractured circumferentially 360 degree around and all the blades were missing from the disk's blade slots. The HP/IP turbine bearing chamber external vent tube exhibited two burn-through holes located just outboard of the IP turbine case connection. The thrust reverser sustained damage to the inner and outer fixed structures. There was additional damage to the left wing and to the fuselage of the aircraft.

A borescope inspection of the No. 2 engine's HP/IP turbine bearing chamber external and internal vent tubes revealed the presence of black coke-like (black carbon deposits from the decomposition of oil under heat loads) buildup in the internal vent tube. The carbon obstruction largely filled the tube cross-section and was concentrated at the midpoint of the tube. The vent tube carries a mixture of air and oil droplets away from the bearing chamber.

Both engines were sent back to the Rolls-Royce facility in Derby, United Kingdom, for examination and teardown.

TEARDOWNS AND EXAMINATIONS

No. 1 Engine Teardown

Disassembly of the IP turbine nozzle guide vane support revealed that the only remaining part of the internal vent tube upper section was a small piece of the upper vent tube section with the IP turbine case connection fitting still attached, together with the outer heat shield . This small piece of the internal vent tube exhibited severe heat distress while the heat shield exhibited only minor pinholing damage. Apart from a short piece of the tube that remained attached to the HP/IP turbine bearing chamber, no portion of the internal vent tube lower section or its associated heat shield was recovered. The fracture surface of the vent tube lower piece appeared torn and exhibited moderate thermal damage.

Closer examination of the IP turbine disk drive arm fracture surfaces revealed heavy mechanical damage, smearing, and localized areas of a blue/black appearance. The drive arm was fractured in plane with the R850 cooling holes. The IP turbine disk was removed from the engine and was sent to the Rolls-Royce material laboratory for a detail metallurgical examination and dimensional inspection. Examination of the microstructure of the fracture surface through the R850 cooling holes in the disk drive arm revealed extensive oxidation and changes consistent with temperatures above 1000 degrees C (1832 degrees F). According to Rolls-Royce, the heat input into the drive arm was a combination of friction and fire.

No. 2 Engine Teardown

A borescope inspection of the entire HP/IP turbine bearing chamber and associated oil tubes revealed that the HP/IP turbine bearing chamber internal vent tube exit pocket¾part of the bearing chamber itself¾exhibited a considerable amount of soft granular carbon deposits at the outlet but that the pocket was not entirely blocked; however, extensive obstruction was noted approximately 2.25 inches outboard into the internal vent tube that prevented forward progress of the borescope.

An airflow check was performed on the blocked internal vent tube and revealed that air was able to pass through the carbon obstruction, indicating that the passage was not entirely blocked. Disassembly of the IP turbine nozzle guide vane support revealed that the HP/IP turbine bearing chamber buffer air tubes were crack free; however, large parts of the heat shield for both the lower internal vent and scavenge tubes were missing. In both cases, the tubes exhibited some fretting damage but neither of the tubes was breached. According to Rolls?Royce, tube frettage at this inboard location is not uncommon but, at the time of the event, there had been no reports of a breached tube.

Carbon Examination

Between February and May 2004, three-dimensional (3-D) neutron tomography was used to determine the extent and morphology of the carbon deposit in the No. 2 engine's internal vent tube. The tomography showed only partial blockage of the tube with carbon deposits. On completion of the tomography, the vent tube was cut open lengthways for visual inspection and analysis of the carbon deposit. The visual examination confirmed the 3-D neutron tomography findings. Rolls-Royce concluded that the morphology, location and geometry of the deposits found in the vent tube of No 2 engine were different from those typically seen on other Trent engines. ExxonMobil also concluded that there was a significant difference in carbon formation in the internal vent tube of No 2 engine and that the geometry of the deposits was unusual relative to that seen in other Trent 700 engine operation.

Oil Samples and Analysis

Edelweiss reported that Mobil Jet Oil (MJO) II was originally used in the incident engines but that, after 2 months of service, the oil was switched to MJO 291. According to Rolls-Royce, Edelweiss was the only Trent 700 operator that used MJO 291 in its engines. Oil samples were taken from the No. 1 and No. 2 engines and from the oil in the flyaway kit that was onboard the incident airplane. Rolls-Royce, Exxon Mobil, and QinetiQ, an independent oil analysis laboratory located in Farnborough, United Kingdom, conducted oil analysis on the recovered samples. The results indicated that the oil in the No. 1 engine was exposed to elevated temperatures, that the oil samples from the No. 2 and the flyaway kit were typical of used and new MJO 291 oil respectively based upon the results of laboratory testing during the original evaluation of the oil for use in this engine, and that no significant evidence of oil contamination was noted in either the No. 1 or No. 2 engine.

Coking testing was conducted on the oil samples taken from both engines and new production MJO 291. The tests confirmed that MJO 291 conformed to industry standards and, although coking test results did vary from facility to facility, they were still within the established criteria for these types of test.

ADDITIONAL INFORMATION

Oil History

When the Trent 700 was introduced into service in the early 1990s, Rolls-Royce approved the following oils for use: AeroShell Turbine Oil (ASTO) 500, ASTO 555, ASTO 560, MJO II and MJO 254. On March 29, 1996, Rolls-Royce added MJO 291 and Exxon Turbo Oil 2197 as approved oils for the Trent 700 engines. App...