Massive branch fell of 80 foot Acer in my garden

[FallenBranches]

Thank you again for your replies. I have just finished cleaning it up and preparing the bigger parts for seasoning. I noticed two things that could be symptomatic of some issue and wonder if I could get feedback. 
 

1) the branches were extremely easy to break off. It was as if the wood was soft and fragile, I could tear most thumb thickness branches off easily with my hands. For comparison, I cut some rhododendron yesterday and there is no way on earth I am breaking a thumb thickness green Rhodi branch off with my hands

 

2) the core of some of the branches was dark brown / looked rotten. I have attached a picture (see below).  The branch on the bottom has a normal centre (pith?) the top one, the centre is discoloured and brown

 

 

[Mick Dempsey]

It’s sycamore which is very brittle and easy to break anyway, so that’s nothing.

I am pretty sure that the pith is irrelevant as well.

 

Sometimes branches fall off tree.

 

Got a pic of the part that broke off?

[Khriss]

4 hours ago, Mick Dempsey said:

It’s sycamore which is very brittle and easy to break anyway, so that’s nothing.

I am pretty sure that the pith is irrelevant as well.

 

Sometimes branches fall off tree.

 

Got a pic of the part that broke off?

It s big Enormous, are you taking the pith Dempsey ? K