What happened
On July 31, 2008, an Airbus A3/10-304, registration OK-WAB, operated by ČSA, experienced a serious incident shortly after departing from New York's John F. Kennedy International Airport (KJFK). At an altitude of approximately 900 feet, the crew noticed significant aircraft vibrations and a thrust imbalance between the two engines. Monitoring instruments revealed that while engine number one was operating normally, engine number two showed a drop in low-pressure turbine speed (N12) to 73% and an Exhaust Gas Temperature (EGT) exceeding 900°C. No warnings were initially displayed on the ECAM.
The crew reduced engine number two to idle power and notified ATC. As vibrations persisted and EGT continued to rise, the crew elected to shut down the engine. During the transition to single-engine flight and the reconfiguration of the aircraft's mechanics, the aircraft exceeded its maximum speed limit for the current configuration for approximately seven seconds. The crew followed the Quick Reference Handbook (QRH) procedures for engine over-limit, single-engine operation, and overweight landing, eventually requesting an ILS approach to runway 31. The aircraft landed at a weight of 147 tonnes, significantly exceeding the maximum landing weight of 124 tonnes. Following the landing, technical assistance was requested due to high temperatures detected on the right-side landing gear brakes.
The investigation
The ÚZPLN investigation focused on the mechanical failure of engine number two. Post-flight inspections and subsequent teardown of the engine in Europe revealed extensive internal damage. Investigators identified that a portion of a first-stage low-pressure turbine (LPT) blade had broken off. This failure triggered a chain reaction of secondary damage, including the destruction of several subsequent LPT stages and damage to the engine casing.
Detailed metallurgical analysis of the engine components showed that while some damage, such as a broken 11th-stage high-pressure compressor (HPC) blade and EGT probe damage, was older, the primary failure was the sudden loss of integrity of the 1st-stage LPT blade. The investigation also noted the presence of organic contaminants and sand on the compressor components, suggesting the ingestion of foreign material during ground operations or takeoff.
Findings
- The primary cause of the incident was the failure of engine number two during the initial climb phase.
- The failure was likely caused by the breakage of a first-stage low-pressure turbine (LPT) blade.
- The breakage of the LPT blade caused extensive secondary damage to the engine's internal structure.
- The crew's response to the engine failure was in accordance with the operator's established procedures.
- The aircraft exceeded its maximum speed limit for 7 seconds during the reconfiguration of flight mechanics.
- The landing was performed at a weight exceeding the maximum landing weight (MLW).