Bjorn’s Corner: Aircraft engines maintenance, Part 2


By Bjorn Fehrm

March 10, 2017, ©. Leeham Co: Last week we started the series how airline turbofans are maintained. We described the typical work scopes and what the intervals were for different single-aisle engines.

Before we can describe the engine maintenance market we must get a feel for the market size for different engine types.


Figure 1. Principal picture of a direct drive turbofan. Source: GasTurb.

We will start with understanding the single-aisle engine maintenance market.

Engine maintenance market

To understand the engine maintenance market, we need to look at what engines are in the market and their use. Data over which aircraft has a certain engine and how much these have flown over the years will be an estimate of engine use.

As the ratio between flight hours and flight cycles is not that different between a Boeing 737 with CFM56-7 engines and an Airbus A320 with IAE V2500 engines, the flight hour profile is also a good proxy for the flight cycles that engines go through in the single-aisle market.

Single-aisle flight data

We have been allowed to show the flight data statistics that Alistair Forbes, Services Research Manager at Rolls-Royce, has collected. He has used OAG (Official Airline Guide) as the database. AOG only captures scheduled flights. It means charter and freight flights are not part of the diagrams. For most single engine types, this is not significant. Regional engine types are not included in the statistics.

Business case

The engines which are interesting for a maintenance company are the ones with many flight cycles and therefore flight hours. To set up a maintenance capability, a maintenance shop must establish a contract with the OEM for information and spare parts. It must also train personnel and certify the facility and people with the OEM and airworthiness authorities for the engine type.

This costs money and there is a need for a constant load on the shop to make it an acceptable business. This is why there will be few shops with a capability to maintain a niche engine, while popular engines will see many shops competing for the jobs.

CFM data

The most used engine for single-aisle aircraft is the CFM56. The graph shows the EFH (Engine Flight Hour) profile for the main variants from 2001 to 2016.  All graphs have the same scale so the curves are directly comparable.

Figure 1. EFH profile for CFM single aisle engines. Source: Rolls-Royce.

The most used engine type is the CFM56-7, which is the type on the Boeing 737NG with 32m Engine Flight Hours (EFH) during 2016. The CFM56-5A and B for the Airbus A320 series are second with 20m EFH.

Pratt & Whitney data

We put together the classical Pratt & Whitney (PW) engines (JT8, PW2000, PW 6000, PW1000GTF) with the IAE (International Aero Engines) engine variants (V2500). PW dominates IAE and it’s essentially an extension of PW after Rolls-Royce left the consortium.

Figure 2. EFH profile for Pratt & Whitney single aisle engines. Source: Rolls-Royce.

The V2500 on the A320 series dominates the EFH with the V2500A5 variant. Total use for V25000 during 2016 was 16m EFH, about half of the most popular CFM variant.


Rolls-Royce delivered engines to the Boeing 757. The diagram shows the maintenance of these engines is a niche market today.

Figure 3. EFH profile for Rolls-Royce single aisle engines. Source: Rolls-Royce.

Next step

Next week we will look at the maintenance shop market for the single-aisle engines. Then we continue with the wide-body maintenance market.

2 Comments on “Bjorn’s Corner: Aircraft engines maintenance, Part 2

  1. I have to say that the explanation of how an engine is used, maintained and rated in these articles is very informative. Prior to reading this, I just thought the more thrust needed, the bigger engine had to be on the plane.

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