Hi,
  I have a bluecard and stay in Munich. My wife may have to stay 10 months outside Germany,
will she have a problem at the port of entry when is back, visa is valid at the time. 
Is a form from foreign office required, should i apply for it. 
Any help is highly appreciated.
Regards,
Vijay

"My wife may have to stay 10 months outside Germany, will she have a problem at the port of entry when is back, visa is valid at the time", yes she will have problem as her visa will not be valid contrary to what is written on it as a date as staying for more than 6 months outside of Germany will invalidate the visa.
"Is a form from foreign office required, should i apply for it.", not a form but a letter from them allowing her to do more than 6 months outside of Germany. You should talk to them and there should be no problem getting it.

D. 

Hi, 
  Thanks for the info, but the Hotline team from bamf.bund has replied its perfectly to ok stay 12 months and the passport control officer also mentioned that to my friend.
Is the letter really required. Please check attachment.

Thanks and Regards,
Vijay