Carrier Fan failures

[Lynn Eades]

I am interested to know about the failures where the generator and fan assemblies fall forward and chew up the radiator. I recall this happening to a couple of local carriers in the last few years and I wonder what actually fails.
I believe the failure is common across the carrier family. Australian pattern carriers have failures and they have no fan extension. They just use Commercial Ford standard parts.
I am aware that the stud in the front of the manifold breaks and that there was an upgrade in the stud.
I am also aware that there was a girdle fitted as standard to later British carriers to stop the whole assembly falling into the radiator.
Questions:
Who has had this happen and can report on what failed?
Does the manifold also fail?
Is the cast iron (original) stronger than the alloy manifold?
Is fan blade failure a primary cause (does a blade coming off, cause the stud to break?)
I understand that riveted carriers are good at shedding fan blades?
Some manifolds have ribs running back from the front while others (maybe early?) don't.
Any feed back on this would be appreciated.