Dozy I beg your pardon. I too am annoyed that they have broken up the Nimrods. I am annoyed too about this T900 failure because the Comet was prone to the same fault as we are focussed on in this thread.
and moving on...
"Solutions for vibration problems involving the excitation of a natural frequency (resonance) are frequently difficult to obtain based solely upon experimental data." Thats what FAG says and moreover:
"Finite Element Analysis (FEA) is a numerical technique that can be used to approximate the structural dynamic characteristics of vibrating mechanical systems, the understanding of which is paramount to any root-cause failure study involving excessive vibrations."
The problem is that FAG have little experience in this field compared to SKF.
This is where METROLOGY began, the original paper from 1955:
http://mdrl.mne.psu.edu/papers/bearinganalyzer.pdf
This is how RR service agents themselves tackle vibration testing in the field, after the engine has left the factory and needs fixing.
http://www.skf.com/files/446130.pdf
And this is a dynamic exploded view of the bearings as they fit into a gas turbine, which is the smoothest running machine known to man: it HAS to be just to stay together.
Engine & gearbox - SKF.com/Industries/Aerospace/Applications
As Annex has told us as reported in his local newspaper:
"since SchaefflerGroup / FAG as the bearing supplier has denied a failure of their bearing(s) as a primary cause"
They did not say this was the first time they had designed and built a series of bearings for an aerospace gas turbine or indeed the entire bearing mounting system from one end of the engine to the other.
So how come they got the contract? Well YES how come?
Thier design had less mass, the mounts were "vibration reducing" and they saw the big cake of the EA business in N America for the B787. They even set up a manufacturing facility in Canada to serve EA. They want to be up there with the new generation of lean engines.
Not a good start!
All replies most welcome.