The picture "Rolls-Royce Trent 900" is taken from Wikimedia Commons. The author is "User:Kolossos", it is freely reused here according to the terms of the particular licenses under which the copyright holder published it (see link above).

The picture "Turbine blade, fir tree" is taken from Wikimedia Commons. The author is "Tomeasy", it is freely reused here according to the terms of the particular licenses under which the copyright holder published it (see link above).