well, i took the chance and flew back knowing that the chain was in the tank (the field was 1:30hr drive vs. 35 min flight from my base and no taxi, bus available) I was also concerned that the chain could block the fuel lines but since the fuel comes from both left and right fuel tank so I thougt if the left one gets clogged the engine can still be fed from the right one.
And yes, i have sent the engineer an e-mail but i don't kow how long until he will reply or address the problem so i wanted to get a second opinion...
*edited for spelling*