Engine MRO Challenges for Different Engines of A320 Aircraft Family
The A320 aircraft family is one of the most successful and widely used commercial airliners in the world. It is powered by a variety of engines, each with its own unique challenges for maintenance, repair, and overhaul (MRO). These challenges can vary depending on the engine manufacturer and model, as well as the specific components and systems involved.
For example, some engines may require more frequent inspections and replacements of certain parts, while others may have specific procedures or tools needed for their maintenance. Additionally, the availability of spare parts and qualified technicians can also pose challenges for engine MRO in the A320 aircraft family.
Yet, let’s embark on a journey to explore the distinctive challenges that each engine, propelling various iterations of A320 derivatives, lays before us. Fasten your seatbelts and let this exploration through the rugged landscapes of the A320 family history, where every engine has a story to tell, commence.
The First Choice
Back in the 80’s, when A320 program was in the early stages of its development, Airbus explored propfan technology, which was considered as a promising option to power the manufacturer’s next generation of aircraft. Experimental at the time, it involved placing a fan outside the engine nacelle, providing turbofan speeds with the economic advantages of turboprops. Ultimately, Airbus opted to stick with turbofans.
The A320 initially featured two CFM56-5-A engines under the wings. The CFM56-5-A engine is a reliable and efficient powertrain that has a proven track record of performance. It is a popular choice for airlines that operate the A320 aircraft family because of its low operating costs and high dispatch reliability. However, it is not without its challenges.
Like most engines of such architecture, the CFM56-5-A is susceptible to fan blade erosion. The fan blades are located at the front of the engine and are responsible for drawing in air. Over time, these blades can erode, which can reduce engine’s performance. This is the common issue for CFM56 engines, as damage to fan blades can be caused by several factors, including foreign object damage (FOD), bird strikes, and erosion from sand and dust.
Being more advanced version of the CFM56-5A, CFM56-5B shares most of the above problems, contributed to various variants of CFM56 engines. Yet, there are some which became more common in CFM56-5B, one of which being compressor blade fouling.
The compressor blades are responsible for compressing the air before it enters the combustion chamber. Over time, these blades can become fouled with dirt and debris, which can reduce the engine’s efficiency. Upon detecting fouling, maintenance shops can deploy a range of corrective measures. Blade cleaning emerges as a crucial task, involving methods like ultrasonic or chemical treatment to rejuvenate the failed blades. In more severe instances, where the grime takes a heavier toll, the option of blade replacement comes into play.
For more comprehensive solutions, an engine overhaul may be required. This process involves addressing the underlying causes of fouling to ensure the overall health and performance of the engine.
Such type of engine is also prone to combustor liner cracking. Responsible for burning the fuel and air mixture, combustor has inner and outer liners, which help to protect the engine from the harsh environment of combustion. Over time, however, these liners can crack or erode, which can lead to a number of problems, including reduced engine efficiency, increased engine wear, and potential engine failure.
Engine operators and MROs can address combustor liner cracking by taking several preventive and corrective measures. On the preventive side, engine operators and MROs can ensure the proper maintenance of the engine, utilize high-quality lubricants, and keep a close eye on the engine’s performance. If cracks do occur, MROs usually employ visual inspection methods to detect and address the issue promptly.
Yet, such inspection poses some challenges as instances of carbon deposits on such liners are frequently mistaken for cracks. To accurately discern the type of defect, a technician, performing such inspection should employ a high-magnification probe, and increased light intensity.
Other Issues with Engines of CFM56 Family
While damage inflicted by foreign objects tends to have more severe consequences on engine fan blades, it is a relatively rare occurrence, yet remains unpredictable. In contrast, the impact of hydro-meteorological factors and sand poses a more constant and unavoidable hazard. Specifically, the combined effects of rain and sand during flight can significantly abbreviate the lifespan of engine blades, presenting a persistent challenge throughout most journeys.
This type of damage proves resistant to elimination, requiring restoration through blade polishing to reinstate partial aerodynamic performance. Such restorative process mitigates the considerable economic losses associated with the frequent replacement of blades and also poses some challenges for MROs.
Firstly, the inspection of fan blades for erosion is a complex task due to their location. MROs need to employ advanced inspection technologies such as non-destructive testing (NDT) methods like ultrasonic or eddy current inspections. These methods allow for a thorough assessment of erosion without the need for extensive engine disassembly.
The Second Choice of IAE V2500
Another engine, which Airbus and its operators choose for its 320-family planes, was the IAE V2500, which got under the wings of A320 for the first time in 1993. Sharing some similarities with CFM56, it is also subjected to the challenges, which are faced by its operators and service facilities. A problem, also common for other turbofans, yet popularly attributed to this type of engine is hot gas ingestion, which occurs when hot gases from the combustion chamber leak into the engine’s bypass duct. This can cause damage to the engine’s components and reduce its performance. This is a less common issue for CFM56 engines, but it can be caused by a number of factors, including cracks in the combustor liner, damage to the seals, and improper engine maintenance.
Back in 2009, several V2500s were pulled out of service after a wider inspection was performed to determine the scope of the problems with the high-pressure compression drum. The issue was quickly determined, and the producer had developed an effective, yet easy and straightforward fix that involved the replacement of some bolts within the compressor. This repair was already being applied to new production engines as well as for these already in service, yet eventually bound for overhaul procedure.
And, of course, there is also a turbine blade wear. Blades of the turbine are located at the back of the engine and are responsible for converting hot exhaust gases into power. Over time, these blades can wear, which can reduce engine’s efficiency and power output. This is a common issue for all turbofan engines and is caused by the wear and tear of normal operation.
PW1100 Engine and Its Challenges
The PW1100 is a newer powertrain for the A320 family. This geared turbofan engine is more fuel-efficient and quieter than the older engines. However, it is also a more complex engine and can be more challenging to maintain.
The above benefits of this engine are mainly achieved thanks to its innovative gearbox which allows both the fan and engine’s low-pressure spool to separately spin at their own optimal speed. Yet, the innovative gearbox also is not without its own issues, which in some scenarios are especially difficult to diagnose and repair.
There is also a common issue, similar to other types of PW1000 engines, which is related to sensor failures. The PW1100 engine uses several sensors to monitor its performance. Sensor failures can lead to engine performance problems and can make them hard to find.
The challenges faced by airlines and MROs in maintaining A320 family engines highlight the changing landscape of aviation maintenance. As technological advancements drive efficiency, they also demand continuous adjustments in maintenance procedures. Through proactive measures, relevant inspection techniques, and close collaboration with aircraft manufacturers, the industry can tackle these challenges and safeguard the unwavering dependability and performance of the A320 family of aircraft.