Wire strike blades

If you mean the "wire cutters" there are blades similar to hack saw blades in the "fork" that hooks the wire to weaken it so it will break when it hits the final sharp blade.  Some birds have one running the height of the windshield on the center brace. 

I thank you for your answer to my question, Melgyver. I saw them on this illustration:

It would seem that there are two of them, the one you described and one on the bottom of the forward fuselage. Just what kind of wire are they supposed to cut? Power lines? May the good lord help them!

An old friend of mine was a Huey pilot in Vietnam, the troops preferred to fly with him because he was good at crash landings. He said he would aim the helo at the trees to strip the rotor blades away from the aircraft. Must have worked, he'd survived over 11 crash landings before a bullet shot up from the bottom of his seat and tore up his colon. He went on to fly with the Navy after that.

There are two, one under and one on top of the fuselage, depending on the aircraft.  Blackhawks and Apaches have two on the botton, one on each landing gear strut arm.  They are designed to cut small, hard to see wires that the enemy may string across valleys or roads that the helos are running up and down.  A power line is way too large for them to cut and can usually be seen. 

Thank you Gino, so it functions like the cable cutters installed on jeeps during WW II. I didn't think about that occurring to a helo flying NOE. It makes good sense.

Different helos have different wire strike protection components depending upon the arrangement of their forward ends and what might get snagged.  A Huey has the big blades on the roof and the chin, as well as heavy wire-like guards at the top corners of the windscreen to keep the wipers from snagging.  A Cobra has the bottom blade set forward of the skids, a small blade just under the nose, a deflector on the front of the TSU, two long deflectors on the forward edge of the canopy, and a blade in front of the transmission fairing.  The cutters do offer some protection from utility wires-- that's why you see the systems mounted on purely civilian helos like Bell 222's.   But high-tension lines are not going to be defeated by the cutters and recently a Blackhawk went down near here after hitting those kinds of wires.