The Reliable Jet Engine

In this series on aircraft and engine technology, I’ve regularly discussed innovations and development. Some people would love see things progressing even faster, but these things take time, especially in the air transport industry, with its high standards and strict regulations. In this blog, I’ll be taking a look at the development of jet engines and how they became so incredibly reliable.

The mid-1950s

Gas turbine or jet engines have been used in commercial aviation since the mid-1950s, when the first jet-powered airliners, including the British Comet and the American Boeing 707 and Douglas DC-8, took to the air.

DC-8 KLM oldie

The gas turbine engine has undergone an incredible evolution since those early days. From a straight jet, in which all the incoming air passed through the engine itself, to the current bypass engines, in which most of the incoming air flows around the central propulsor.

A lengthy process

This modern design has two major advantages: the engine produces much less noise and fuel consumption is much lower. Developments like this don’t happen overnight, mainly because the technology is complex and because of the strict safety and reliability requirements that apply for all aspects of aircraft engineering and operations.

How long does it take to develop a new engine?

Roughly speaking, a manufacturer will spend around 10 years developing and introducing a new engine. The initial design phase is, of course, guided by the aircraft type for which the engine is intended. Throughout the design process every component is carefully tested, which eventually leads to the first tests of the fully assembled engine in a special test cell.

Engine test cell

During these ground tests, the engine is subjected to all sorts of extreme forces and operational scenarios. Later, the engine is also tested on specially designed test aircraft.

Once the engine has successfully completed airworthiness certification, it may be used for commercial aviation.

This process takes many years to complete and the main reason for this is safety. It is this lengthy and meticulous process that has brought commercial aviation to where it is today: a safe and reliable means of transport. The aviation industry continuously seeks ways to improve existing engine types. This process goes on throughout the working life of an engine, during day-to-day operations. It never stops.

Engine test cell

What is the lifespan of an engine and aircraft type?

An aircraft can remain in commercial operation for up to 25 years. And engines may have an even longer lifespan, partly because of the preceding development and certification period. But also due to the fact that there are certain engine types which are used at different aircraft models, optimizing the economical usage.

787 engine

And exactly how reliable are turbine engines nowadays?

In the early days of the Jet Age, engines had to be removed for a full overhaul after a relatively short span of time in operation. This operating time is usually expressed in flight hours. Back in those days, an engine was removed and overhauled after 2,000 flight hours.

Nowadays, operating time between major overhauls has been extended to around 20,000-25,000 flight hours. We fly wide-body jets equipped with just two engines to all corners of the globe. This evolution can be mainly attributed to the enormous gains in engine reliability over the decades.

Boeing 777

So, when you next board a plane, maybe take a moment to remember that the industry spent 10 years ensuring that the aircraft and its engines are perfectly suited to your flight, and that the process of ensuring their reliability goes on constantly. It never stops.

Posted by:   Rob Duivis  | 
Join the conversation Show comments

Kostas Charizanopoulos

Excellent Article!

John Beshoff

Very informative..I would like to know what is most common maintenance problem encountered once an engine is periodically serviced particularly on the larger GE units on the B-777-300er?Thank you.

Rudy Jakma

Concise but very informative.
To illustrate the development of the jet engine and the increasing importance of the “bypass” section: not all that long ago it was possible to attach an engine as a pod to another aircraft, either to ferry it to an aircraft stranded at an outstation, or to flight test it. The conventional engines were a safety margin in the event of failure of the as yet untested and not certificated prototype.
Nowadays this is not common any more – if the procedure of attaching an extra engine with streamlined cowling can be called that.. Increased reliability, but also the dimensions of the fan make this impractical if not impossible, and rarely necessary.

Alan Boyle

Great article, I would like to see more technical articles. Can you explain how the by-pass gas turbine works, where does the propulsion force come from when the air is not forced directly through the engine?

Andre Costa e Silva

Excellent! Rob, as I fly frequently KLM GIG-AMS with 787-9 I would like to know what is the KLM situation with respect to the TRENT 1000 RR problems. Have you been able to correct all the problems with IPC blade cracking?

David Robertson

I do not think that KLM uses Rolls-Royce Trent 1000 engines on its 787–9 dream liner your plants. I am formation is that KLM only uses GE GEnx engines. Wise choice

Jagath Rupasiri

A valuable article.



Tony Barr

On a recent Delta flights from MSP to STL, we were stranded mid field for almost 5 hours at the de-icing station because of snow blowing into the engines after shut-down. What can of filters may be built onto engines to prevent this? Eventually, a pick-up truck arrived with a mechanic complete with broom and step ladder. Not high tech, but combined with the apex of human evolution….

Fred Lammers

Very Nice story

J.G.A.M.van den Bosch

same as Rob, have been involved with gas turbine engines, understanding article, nice story,Rob !

john godguidance leonard

sir, i am an aircraft lover and there is this fan blade i developed and i would
like klm to help in under study it and proof it for use. please it awesome and
can go faster if improved.

john godguidance leonard

this fan blade with my personal test it gives me more inflows of air than normal
aproximetly 20times the speed of the normal fan blade.

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