What happened
On July 27, 2006, an Air Nostrum BOMBARDIER CRJ200 (registration EC-IJF) was performing a scheduled international passenger flight from Barcelona to Basel. While climbing through 23,515 feet over the Mediterranean Sea, the aircraft experienced a loud bang and intense vibrations.
Immediately following the impact, the crew received multiple warnings, including left engine low oil pressure, a left engine reverser unlock, and smoke in the lavatory. Seven seconds later, a fire warning was triggered for the left engine. The crew initiated engine fire procedures, shutting down the engine 16 seconds after the warning. Despite discharging both fire extinguishing bottles, the fire could not be extinguished and persisted for nearly ten minutes.
The crew declared an emergency and returned to Barcelona. During the approach, the crew executed a 3/60-degree turn to manage altitude. The aircraft landed safely on runway 25R using only the right engine. Following the landing, the aircraft was evacuated via the right-side doors. All 48 passengers and crew escaped without injury, though the aircraft sustained heavy damage to the left engine.
The investigation
Investigators examined the aircraft's flight data, cockpit voice recorder, and engine components. The inspection of the left engine revealed that a fan blade had detached, leading to a massive imbalance. This imbalance caused a chain reaction of mechanical failures, including the separation of bolts in the high-pressure turbine (HPT) stator case flanges, the detachment of the accessory gearbox, and the loss of the fan access cowls. The investigation also noted an error in the assembly of the rigid elbow connecting the variable geometry (VG) head line to the main fuel control.
Regarding the crew, while the emergency was managed successfully, investigators found that the distribution of tasks during the emergency did not align with the operator's established criteria.
Findings
- The primary cause of the left engine failure was the separation of a fan blade caused by dwell-time fatigue cracks. These cracks originated from specific microstructural features (aligned alpha colonies) created during the blade manufacturing process.
- The resulting high fan imbalance caused secondary structural failures, including the separation of the LPT module and the detachment of engine cowls.
- The crew's management of the emergency was complicated by the simultaneous appearance of multiple cockpit warnings and a persistent engine fire.
Safety action
- It is recommended that Air Nostrum reinforce technical crew training, specifically focusing on leadership, decision-making, and task distribution during abnormal and emergency situations.