engines are two stage and not connected to MGB.
That statement needs expounding upon I do believe.....because if they are not connected to the MGB....what turns the Rotor Blades in powered flight?
I can't find a report from survivors referring to the distinctive noise made by a jet engine when heard from close proximity (even when shutting down)
Perhaps neither engine was running at the time of impact and entering of the building structure by the aircraft? Likewise....there was no post crash Fire of any kind if reports are correct.
During a fairly recent US Based EMS Helicopter crash there were eye witness reports of "Sparks" being seen coming from the aircraft prior to its crashing and killing all aboard. it too was an EC aircraft.
As to what the cause of that crash i am not sure.
That an Eye Witness may report seeing sparks...is not unheard of and in/of itself cannot necessarily be given a lot of credence unless corroborated somehow.
Eye Witness reports are quite susceptible to being inaccurate for any number of reasons.