If, like me, you are wondering what goes on inside a jet engine the site below from Rolls Royce might help. As a pilot I merely used the thing, in my case four Rolls Royce RB211-524s on a Boeing 747-200 and very good they were too.
I also had a flight engineer who helped by ensuring that I didn’t do anything too stupid! Nowadays though, with FMS and FADEC (Full Authority Digital Engine Control) the computers do it all. One no longer has to set the power manually, while making small adjustments to ensuring that neither the N1, N2, N3 nor EGT limits were exceeded.
Most large turbofan engines have two spools, but the Rolls Royce RB211 and Trent series have three.
In all jet engines, whether straight jet, turbofan or turboprop, the most highly stressed area is the hot end, in particular the HP turbine disc and blades. Just click on the picture below to look at an animation by Rolls Royce of a journey through a jet engine.
And if you want to know how complicated a turbine blade is, take a look at page 11 in this document which has a picture showing the complex cooling ducts within the blade itself:-
We should always remember how much less reliable aircraft engines were in the past. In the 1950s, when the long haul routes were dominated by the Boeing Stratocruiser, Douglas DC7C and Lockheed Constellation, those magnificent mighty radial engines had frequent failures. The introduction of the Bristol Britannia was delayed by icing problems with the Proteus turboprop engine. And the Boeing 747, powered by Pratt & Witney JT9D-3s, suffered from engine surges in its early days. It was not infrequent, for all these aircraft types, to arrive on three engines and sometimes even on only two.
Whatever the ATSB’s interim report on the Qantas incident reveals (expected on 3 December) it is good to know how extraordinarily reliable modern jet engines are.