Repeating question of bolt shearing in D/Ws drum shaft?

Question

The equipment was repaired by our company's OFE workshop which has experienced mechanics.
OEMs bolts were only used and no change in spacing from that of OEMs design and this is one of the rare failure encountered in the project

Answer 1

if it was a rare failure then further investigations would be required which would require more data. the info provided is insufficient

Answer 2

An engineering failure investigation of this kind is beyond the scope of an internet answer service like this as it requires a lot of information on the load history, environment, microscopic appearance of the failed surfaces, metallurgical analysis of the materials, checking of quality records etc.

If your company does not have a failure investigator then you could hire a consultant.

You could also ask the OEM to investigate the failure.