Well, this week started out with a bang so to speak. Was working on the helicopter, we got paged to do an interfacility transfer. We lifted enroute. I sat in the back for this flight while my partner was up front with the pilot. We had just switched out to a loner helicopter while ours was in the shop getting prepared for the crews to use night vision goggles. Upon lifting we discovered that the"ICS" in the aircraft was not working, therefore  my partner and pilot can't hear me and I can't hear them. The only thing I could here was the pilot giving radio calls to a local airport tower. We were at about 3500 feet when all of a sudden we hear and feel an extremely loud "bang"it literally felt like something hit us on the bottom of the aircraft right under where I was sitting. I hear my pilot say "what the $%^& was that? As he immediatly does a high and right to get some altitude. I hear him tell tower, we've been hit by something, I am going to do an emergency landing in a field. I have no radio communications with our dispatch center. He then does a hard bank left to land in a field my partner showed him. As we turn towards it the sun was so bright it blinded them and they aborted that landing. He then does another hard bank right to attempt another field. Now keep in mind I can't hear them all I know was we were hit and now are flying all erratically all over the place.  I thought the aircraft was unable to be controlled. I get on my cell and call the hospital on a known recorded line. I thought if we go down I want someone to know something. So I talk to the Dr. that  answered the phone, tell her what is going  on. The nurse reaches back & grabs my arm, asks if  I dropped something I say no. Then I hear  the pilot say we are close enough to the airport that we are going to try to make it there, that way we are closer to emergency support should we need it. The pilot tells the tower  the aircraft seems to be reponding appropriatly. We make it and land, in the meantime, my boss and Jimmy are both enroute to the airport, they had been notified once our dispatch center heard what was  happening.  Long story short, our mechanic is called, the aircraft checked out, it is found that our boot (big plastic piece pice that is held on by several clamps, & is  wrapped around the mast to prevent rain, bird droppings etc from entering the engine area. ) From the marks on the helicopter it had flung off in flight, hit our tail boom on opposite side of the tail rotor. Thank God it didn't knock out our  tail rotor! From what I've been told this only happened  one other time & the ending was not as good  as ours. God must have a reason for me to still be on this earth & i'm glad I am.