What happened
On December 14, 2018, a commercial flight, AR1324, operated by Aerolíneas Argentinas S.A., was en route from Ezeiza International Airport to Punta Cana, Dominican Republic. While cruising at 31,000 feet, the crew of the Boeing 737-800 MAX, registration LV-HKU, detected vibrations in the left engine. The vibration level reached 4.2, approaching the maximum allowable limit of 5.0.
Following the procedures outlined in the Quick Reference Handbook (QRH) for high engine vibration, the crew initiated a descent to 27,000 feet. To ensure the aircraft was within the maximum landing weight limits, the crew entered holding patterns at 6,000 feet to consume fuel. The aircraft subsequently performed a precautionary landing at Tucumán International Airport. The landing was completed without incident, and all passengers and crew disembarked safely.
The investigation
The investigation was initiated after the JIAAC became aware of the event through media reports, as the incident was not formally reported by the operator at the time of occurrence. Technical evaluations of the left engine, a CFM-56 Leap-1B, revealed that the number 7 fan blade had sustained damage due to friction against the abradable surface.
Following the incident, the aircraft was transferred to Ezeiza for repairs. Maintenance crews replaced the damaged blade and repaired the abradable section of the engine, allowing the aircraft to return to service on December 18, 2018.
Findings
- The primary cause of the vibration was identified as crystal icing occurring on the engine spinner.
- This phenomenon, characterized by ice accumulation behind the spinner, likely caused the engine imbalance.
- This event marked the third occurrence of similar fan blade friction issues within the operator's new fleet of 737-MAX-8 aircraft equipped with Leap-1B engines.
- The incident was not officially notified to the authorities in a timely or proper manner.
Safety action
- The operator should monitor the performance of CFM-56 Leap-1B engines during flights through meteorological conditions prone to crystal icing and share findings with the engine manufacturer.
- The importance of timely incident reporting must be emphasized to ensure the preservation of critical evidence for safety investigations.