Well it's not a fan belt but I know what you mean it's the poly V belt runs water pump air con alternater etc.
One problem that can cause this multiple belt fraying and breakage is where the main drive pulley wheel shed the outer vulcanised rubber casing.
best seen on my my site
Bert Rowe's-A-class info. Poly 'V' Belt, Crankshaft pulley wheel problems.
And it's not easily spotted so take a look.
