737 MAX and A320neo Engines Failure Risk Found Airlines Asked CFM To Check PROBLEM

CFM International have identified a potential problem with Leap-1A and Leap-1B engine, as used on the Boeing 737 MAX and Airbus A320neo aircraft, have been found to be suffering from coking of fuel nozzles at a much faster rate than anticipated.

CFM have found an issue with the Leap-1A and Leap-1B engines which are used on both the 737 MAX and A320neo. The issue involves a carbon build up on fuel nozzles which could lead to engine failure.

What’s the problem 737 MAX and A320neo Engines facing?

Gas turbine engines are highly susceptible to a buildup of carbon, in a process known as coking. Deposits from evaporated fuel and other material create obstruction to the fuel nozzles,This obstruction can lead to uneven temperature flow within the combustion chamber and can cause hot spots to develop inside the high pressure turbine. These hotspots are responsible for premature wear and, potentially, to the failure of the engine.


Coke is the solid residue created when oil undergoes severe oxidative and thermal breakdown at extreme engine temperatures. The higher the temperature, the harder, blacker and more brittle the coke/deposit residue.

Coking classifications include: 1.Thin film 2.Mist/vapor 3.Puddles 4.Dynamic

Various factors and environmental conditions can contribute to coking happening, including the temperature of the engine at shutdown.The phenomenon is not about the nozzle design itself , it is caused by temperature-induced evaporation of unburned fuel, which leads to hard deposits of solid carbon being laid down in some parts of the engine, particularly the fuel nozzles spraying fuel into the combustor.

👉 Since the problem was identified, all carriers with engines which were beyond the revised threshold for nozzle swaps were asked to inspect their engines. Inspections have turned up issues on around 1% of the engine fleet, all on the Leap-1B engine used on the 737 MAX.

Although as yet no problems have been found in the Leap-1A engines, as used on the Airbus A320, some carriers are also being asked to inspect their equipment to ensure all is well

Author: TECH SINGH Urs


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