On the Airbus A320 family, there are 2 engine types available: the CFM International CFM56 and the IAE V2500. There are numerous characteristics to both engine types which suit particular sets of operations.
As of 2022, approximately 65% of Airbus A320 aircraft types are powered by CFM International CFM56 engines while the remaining 35% are IAE V2500 powered.
However, for most applications, the CFM56 engine is regarded as the optimal type. This is primarily due to:
- Higher level of reliability
- Economical – the CFM56 is a more efficient engine type for most aircraft (A318/A319/A320 in particular)
- Lower idle thrust – this makes the CFM56 more fuel efficient when stationary on the ground.
- Engine start procedure is shorter than that of the V2500 start up – approximately 30 seconds on CFM56 versus 1 minute on the IAE V2500.
These reasons make the CFM56 the preferred engine for most operators. However, the IAE V2500 has slightly higher thrust settings which make it ideal for some operational environments. As a result of this, it can be more commonly found on the slightly larger Airbus A321 aircraft.
A primary trend found when comparing these 2 engine types is that the CFM56 has lower maintenance costs while the V2500 engine typically has a lower fuel burn but with higher maintenance costs.
IAE V2500 powered aircraft are typically preferred for longer flights were the type’s fuel efficiency/savings are more noticeable to that of a shorter sector.
One of the primary differences in engine architecture for the V2500 is that indications are read through the EPR (Engine Pressure Ratio) parameter rather than the N1 on the CFM56 engine.
The difference in this regard is that the N1 parameter is used to set thrust via the speed of the bypass fan while EPR measures thrust by the pressure ratio recorded across the engine.
IAE vs CFM A321
On the larger A321, there is a higher payload capability to that of the smaller A320 family variants. This is due to the certified Maximum Take off Weight (MTOW) being 93.5 tonnes, 15.5 tonnes higher to that of the Airbus A320.
With this higher payload capability, it makes economical sense to have engines with higher thrust levels. The certified maximum take off thrust rating for the IAE V2500 is 31,600 pounds of thrust (lbf) while the CFM56 take off thrust rating is between 27,000 and 30,000 pounds of thrust (lbf).
These thrust ratings vary based on the specific engine variant installed on the aircraft however they generally fall within these ranges.
Factors Considered When Selecting Engine Type
As discussed above, there are a plethora of operational factors taken into consideration when an operator is selecting aircraft with different engine types available.
The primary operational factors influencing which engine type is selected include:
- Average sector duration/flight time on the operator’s route network
- Maintenance and fuel burn costs – IAE V2500 for fuel efficiency or CFM for lower maintenance costs?
- Profile of airports – runway lengths and airport elevation
- Market availability – are engine types and parts easily available and accessible to operator?
- Customer support availability and pricing – which engine type provides better value?
In most fleets, the operator generally tends to operate one engine variant – this is predominantly due to parts commonality, in which it is usually cheaper to acquire and manage parts for one engine type rather then two.
Engine Type Designations
Over the years, several variants of engine types usually emerge. Each variant differs slightly in terms of performance specifications – Certified Take off Thrust (lbf) and Thrust Specific Fuel Consumption (TSFC).
With each new variant, there is a requirement for the aviation regulatory authorities to grant certification and approval for the types.
To distinguish between different engine variants, a 2 digit suffix is assigned to the end of the aircraft variant.
These suffixes provide an easy means of identification and clarity in regards the specific engine type installed on the aircraft.
For example, an Airbus A320-200 with CFM56-5B4 powerplants is assigned aircraft type Airbus A320-214. The -14 suffix being the section that outlines the engine type.
This suffix system differs greatly to the Boeing suffix system, in which the last 2 digits of an aircraft type is a customer code, which is a unique designation given to operators.
Airbus Engine Mode Selector Crank