BMW Repair: Washer dropped into oil filter housing, oil filter housing, center tube

Question
I dropped the washer from the long bolt for the cap to the oil filter housing down into the center tube of the housing.  It slipped back toward the engine out of reach.  I think the center tube is the return to the oil pan.  Is that correct, and if so, can I assume that the washer is down in the oil pan and therefore not a problem?  What do you recommend?  
Thanks in advance!!

Mark

Answer
Try fishing with a strong magnet. If it hasn't moved too far, you may be able to retreave it.

might be OK to leave it in, but I wouldn't risk it.  If you think it may have dropped all the way to the pan, you may want to drop the pan.  Before you do, drain the oil.  You might get lucky, and have it come out with the oil.