Vibrations

Did someone leave a "shifter" inside it?

This is not 'shifter'! This is called 'paiepe wrenchh'

Another name is adjustable spanner

In New Zealand that device is called a nut f....er.

The best people to ask are those that form the team that have been working on it prior to its reassembly. Use of the word <...We...> implies that there are at least two of them, after all.

Quite what a bunch of well-meaning, anonymous strangers are supposed to bring to the party is anyone's guess.

<unsubscribes>

They can do an radiography of the complete equipment to rule out the possibility of any entrapped tools..

Lots of things.

Did you follow the proper shut down and cooling procedure before tearing it apart?

If not, you may have warped the shaft.

Bearings could have been installed improperly.

Regardless...you'll find out what you did wrong, when you tear it back apart. There's no other way.

In order to understand what you calculated wrong you might want to expand on what you calculated in the first place.

If with miscalculation you mean "mistakes" there might be plenty. What has been changed and why was the overhaul necessary?

Are both jets working with the same parameters?

This needs far more information to even make an educated guess than possible can be presented in an anonymos forum.

But as a second guess I think there might be an Irish Screwdriver missing in the toolbox . . .

Are the shafts for-sure coaxial?

Here's a question.. why are you asking us?

Get them back in to fix it.. it's not rocket science!

Firstly, are you actually experiencing vibration ? Have you felt it, or is it just a reportable input from a field sensor (accelerometer) to the management system causing the trip?

Not uncommon for field sensors to require calibration/ become faulty etc..

I recall setting older Bentley Nevada accelerometers with an instrument called a 'Wobulator'...

Another possibility is the alignment, which should have been re-done from scratch, if either the generator or the turbine was loosened from their mountings.

In any case, too little information given to make an educated guess...what did your 'overhaul' comprise eg did you replace turbine blades, did you separate the generator from the turbine and overhaul at a remote location etc.. etc..

can I get the spec on that "Wobulator"?

Is it made by the same company that makes the "gangaling pin"?

Misalignement

Imbalance of the turbine rotating elements

Some items missed/forgotten during re-assembly.

Did not follow a strict procedure for this operation (Dismantling-replacing-reassembling), which is supposed to be outlined in a document or manual ...

Should have brought in qualified Rolls Royce team to do the job and they would have been responsable for the outcome.

Do you have a vibration issue when the alternator is disassociated from the engines?

How about when only one engine is coupled to the load? (you said twin)

Is there a gear box between the turbines and the alternator in this set up?

Pulling the thing down is the only way to find out where you miscalculated ( is that the same guessing incorrectly?), but as you take it apart try to run it (if possible) as you go in differing states of assembly. You may not have to pull it completely apart.

Apart from firing this up is there any other way of rotating the assembly?

How about answering some of the other questions from the less flippant correspondents here? ( i have to confess that i was tempted to post a picture of a socket set with an empty slot in it..not helpful)