What happened
On July 12, 2014, at approximately 09:25 UTC, an Airbus 330-202, registration CS-TOO, operated by TAP Portugal, was performing a scheduled flight from Lisbon Airport to São Paulo – Guarulhos, Brazil. During the initial climb phase, approximately 1 minute and 12 seconds after takeoff from runway 03, the aircraft reached an altitude of about 1,300 feet when engine number 2 suffered a failure.
The failure was a contained event, meaning the engine casing prevented major damage to the aircraft's airframe. However, the failure caused severe internal damage to the engine components and resulted in the release of debris. The flight crew successfully shut down the affected engine and elected to return to Lisbon Airport. While the aircraft sustained no structural damage, the release of debris from the engine was powerful enough to damage car windows and house windows on the ground near the Camarate area. There were no injuries to the 232 passengers or 11 crew members on board.
The investigation
The GPIAAF investigation examined the engine components, flight data from the FDR and CVR, and maintenance records. The investigation confirmed that the aircraft's mass and center of gravity were within limits, the fuel was uncontaminated, and the flight crew performed their duties according to procedures, maintaining a calm and proactive cockpit environment. The investigation also looked into the maintenance history of engine ESN 811471 and the environmental factors affecting engine degradation.
Findings
- The primary cause of the incident was low temperature hot corrosion (Type II), which induced cracking beneath the fixing platform of the High Pressure Turbine (HPT) stage one blades, leading to blade separation.
- The engine had reached a higher number of cycles since new (CSN) than desired for removal due to scheduling difficulties between the operator and the manufacturer regarding a planned "Quick Turn" maintenance event.
- The engines were subject to corrosive elements, including salt, dust, sand, and pollution, due to operations in maritime and dusty environments.
- High sulfur content in international aviation fuel contributed to the corrosive environment.
Safety action
Following the investigation, the GPIAAF issued safety recommendation SR nº 13/2016 to General Electric (GE), advising the manufacturer to consider more conservative removal thresholds for HPT blades on CF6-80E1 engines based on assessments following shop visits or quick-turn maintenance. In response to the incident, TAP Portugal implemented a more conservative threshold of 3,400 cycles for the removal of HPT stage one blades.