Non-Synchronous Vibration Concerns: EASA Mandates New Inspections for LEAP 1-A Engine on A320 family

The European Union Aviation Safety Agency (EASA) is addressing non-synchronous vibrations (NSV) found in CFM International LEAP-1A engines utilized on Airbus A319neo, A320neo, and A321neo aircraft. These vibrations have prompted the issuance of an airworthiness directive (AD) by the regulator.

EASA has identified specific engine components, particularly the number 3 bearing spring finger housing with a designated part number, as being implicated in these vibrations. These parts are specified in CFM International's Service Bulletin (SB) LEAP-1A-72-00-0504-01A-930A-D Issue 002. CFM International released a corrected version of this SB in October 2023, prompting EASA to propose its AD on October 25, 2023.

However, the regulator has cautioned that the impacted components within the LEAP-1A engines could experience accelerated wear, potentially leading to increased non-synchronous vibrations (NSV). Left unaddressed, this condition could trigger engine stalls or secondary air system seal rubs, reduce cooling airflow, or elevate temperatures within turbine internal cavities. Such consequences could ultimately result in high-pressure turbine (HPT) disc failures, releasing high-energy debris and potentially compromising aircraft control.

In response, EASA has mandated the monitoring and assessment of NSV. Depending on the findings of operators, affected engines must be removed from commercial service and have the faulty number 3 bearing spring finger housing replaced before being cleared for passenger operations.

Operators are required to assess NSV in their LEAP-1A engines within 125 flight cycles (FC) from the effective date of this AD, which is May 6, 2024. It's important to note that a single flight cycle is counted from the moment an aircraft takes off until it lands at an airport.

EASA has additionally mandated the inspection of the stage 2 high-pressure turbine (HPT) nozzle assembly honeycomb and the HPT stator stationary seal honeycomb. Depending on the inspection results, airlines may need to replace either one or both of these honeycombs. Following the initial inspection, airlines must continue to evaluate NSV at intervals not exceeding 125 flight cycles (FC).

Moreover, unless operators have already replaced the affected part, at the next opportunity such as a shop visit or before the affected part reaches 9,900 FCs since new, whichever comes first after the directive's effective date, carriers must replace any identified affected part as outlined in the CFM International Service Bulletin with specific serial numbers.

Globally, Airbus has delivered 1,756 Airbus A320neo family aircraft equipped with 13 LEAP-1A engine subtypes to operators. However, it's important to note that not every engine will be affected by the directives from regulators, as CFM International's Service Bulletin specifies specific serial numbers and part numbers for the number 3 bearing spring finger housing.