Originally Posted by
Thomas coupling
..... I would be keen to get a very close look at the combiner gearbox........
Agreed. I had a partial combining gearbox failure on another type. One engine then oversped when the shear shaft broke as designed and the engine automatically shut down at its overspeed limit. Fortunately my combining gearbox failure allowed the other engine to keep going. Maybe this crew were not so lucky and both engines shutdown as a result of a catastrophic combining gearbox failure. Not saying it was the case, just floating an idea.