aviation-EASA: Premature coking of injectors on Airbus A321neo Leap engines

The European Aviation Safety Agency (EASA) has published an urgent airworthiness directive pointing out a specific problem with the CFM LEAP-1A engines installed on newer Airbus A321neo models. These engines, known for their high efficiency and environmental friendliness, are showing signs of premature coking of the injectors. These problems, which currently appear to be limited to aircraft of a specific operator, could have far-reaching implications for the operation of the affected aircraft.

The EASA airworthiness directive, which takes effect on September 20, 2024, mainly affects seven Airbus A321neo aircraft delivered to Saudi Arabian Airlines between April and December 2023. In addition, the directive covers three other A321neo aircraft to be delivered to the same airline in the near future. EASA points out that the injectors of the CFM LEAP-1A engines on these aircraft can coke prematurely, potentially affecting the performance and safety of the engines.

Coking, which is the build-up of fuel residues on the nozzles, can cause serious technical problems. This can trigger the activation of a relief valve and affect the thrust control of the engines, which is critical for the safety and efficiency of the aircraft.

Background of the problem and current research

The problem of premature coking in the injectors was first identified on the Airbus A321neo models mentioned. EASA has not published detailed root cause investigations, but premature coking of the nozzles is a concern as it can not only affect engine performance but also potentially lead to unforeseen maintenance and operating costs.

The airworthiness directive requires affected airlines to replace the affected parts within ten takeoffs and landings after the directive comes into force. This ensures that the engines continue to meet the safety and performance standards required for the operation of passenger aircraft.

Technical and operational impacts

Premature coking of injectors in engines such as the CFM LEAP-1A can present a number of engineering challenges. It can impair combustion efficiency, which can lead to improved engine performance. In addition, clogged injectors can limit control of the engine’s thrust, leading to unsafe flight operations and increased maintenance requirements.

For airlines, this means additional maintenance costs and potentially unexpected aircraft downtime, which can increase operating costs and impact flight schedules. Therefore, rapid response and replacement of affected parts is critical to keep aircraft operating safely and efficiently.

Responding to unsafe conditions

Airbus and CFM International, the manufacturer of the LEAP-1A engines, are under pressure to find a quick and effective solution to the problem. Both companies have acknowledged the EASA warning and may be working on further investigations and solutions to identify and resolve the causes of the injector coking. While the exact cause of the problem has not yet been determined, both EASA and the manufacturers involved are expected to work closely together to ensure the safety and reliability of the affected engines.

The aviation industry relies heavily on the reliability and safety of its engines. Problems such as premature coking of the injectors in the CFM LEAP-1A engines can have a significant impact on operating costs and airlines. EASA has taken an important step to address the problem and the airlines concerned must ensure that they implement the necessary maintenance actions in a timely manner.

The case will be closely monitored as it may have implications for other aircraft and engines of similar design. It remains to be seen how quickly and effectively the manufacturers can fix the problems and what long-term measures will be taken to improve engine reliability.