Bjorn’s Corner: Aircraft engine maintenance, Part 4

 

By Bjorn Fehrm

March 24, 2017, ©. Leeham Co: After covering the maintenance market for single-aisle engines, time has come for the engines used on wide-body aircraft. The engine maintenance for a wide-body engine is a bit different to the single-aisle engine. The difference is caused by the longer flight times for the wide-bodies. This makes the flight time wear a more dominant maintenance driver than it is for the single-aisle engines.

The changes in overhaul work caused by the difference in flight profiles and the lower number of engines in the market (compared to the single aisles) will affect how the overhaul market is structured and who are the dominant players.

Figure 1. Principal picture of a tri-shaft turbofan for the wide-body market. Source: GasTurb.

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Bjorn’s Corner: Aircraft engine maintenance, Part 3

 

By Bjorn Fehrm

March 17, 2017, ©. Leeham Co: In the last Corner,  we showed graphs of the yearly flight hours for engines on single-aisle aircraft. Now we will deduce the market for engine overhauls from these graphs.

These will show which engines generate a maintenance volume that is interesting for engine overhaul companies and which engines are niche.

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

Based on the market size, we will then go through how an engine is maintained when new, mature and at end-of-life.

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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. Read more

Bjorn’s Corner: Aircraft engine maintenance, Part 1

By Bjorn Fehrm

March 3, 2017, ©. Leeham Co: We will now go through how airline turbofans are maintained. First, we will describe the typical work which is performed, then look into the markets for engine maintenance.

In the markets for engine maintenance, we will look at who the players are, how they are related to the engine OEMs and why the market dynamics are very different between engines for single-aisle aircraft and wide-bodies.

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

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Bjorn’s Corner: Aircraft engines in operation, Part 6

By Bjorn Fehrm

February 24, 2017, ©. Leeham Co: After having analyzed how the engine gets stressed during different phases of flight, we now look into how engines are used. The de-rating of engines for takeoff is important, as not 100% thrust is needed for all takeoffs. If the aircraft is lightly loaded or is taking off from a long runway, with low temperatures or altitude, the engine can be thrust de-rated so that it experiences less stress.

Once in the air, the engine is run below maximum settings by use of cost-index. These actions will result in less fuel usage and also longer engine operation between overhauls. We will now finish the operations part of our engine clinic with how airlines keep the engines away from the workshops by swapping the engines between fleet aircraft.

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

A visit to the engine workshop costs in the millions of dollars, so the longer the engine can operate before a shop visit, the better. Read more

Bjorn’s Corner: Aircraft engines in operation, Part 5

By Bjorn Fehrm

February 17, 2017, ©. Leeham Co: In our journey of an airline engine’s life, we will now look at the maintenance which is necessary to keep it fit for flight.

An engine is only in top condition once in its life, at delivery. As soon as it’s operated on the aircraft, in-service wear of its different parts will reduce its performance.

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

The engine manufacturer’s prescribed maintenance is designed to keep the engine in good health during its life, despite all its hardship. Read more

Bjorn’s Corner: Aircraft engines in operation, Part 4

By Bjorn Fehrm

February 10, 2017, ©. Leeham Co: We now continue our journey how an airline engine is operated during a typical mission.

Last week we explained basics for engine control and Take-Off flat-rating. We now continue with Climb, Cruise and Max Continuous ratings and why these are important.

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

We also touch on de-rating and Cost Index and how these affect how the engine runs.

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Bjorn’s Corner: Aircraft engines in operation, Part 3

By Bjorn Fehrm

February 3, 2017, ©. Leeham Co: In the last Corner, we went through how our airliner engine reacts to the different phases of flight, including what happens when we operate in a hot environment.

We also showed how engine manufacturers make a series of engines with different thrust ratings by de-rating the strongest version through the engine control computer.

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

We will now look deeper at how engines are controlled and why so-called flat-rating is important. Read more

Bjorn’s Corner: Aircraft engines in operation, Part 2

By Bjorn Fehrm

January 27, 2017, ©. Leeham Co: In the last Corner, we began looking at the in-service operation of a Turbofan. We covered how thrust and fuel consumption varies in the different phases of an airliner’s mission.

Now we will dig a little deeper into how a mission will stress the engine’s different parts.

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

With this knowledge, we will later look at how operators make sure their engines are safe and in good operational condition over the 20 years life of an aircraft. Read more

Bjorn’s Corner: Aircraft engines in operation

By Bjorn Fehrm

January 20, 2017, ©. Leeham Co: We have now covered the technology around airliner turbofans. Now it’s time for the real stuff: their operational life. Most decisions that an engine designer does is about how the engine shall function in practice.

To understand a typical cycle of an airliner engine and the stresses it endures, we will follow an engine during a typical mission.

Figure 1. A principal picutre of a direct drive turbofan. Source: GasTurb.

We chose a single aisle mission because most flights are with single aisle aircraft and the cycle these fly is the most stressful for an engine. Read more