Mac & Mac's Pick: Ground Resonance

By WEEK Producer

February 23, 2012 Updated Feb 23, 2012 at 11:30 PM CDT

Brazilian investigators are now looking into the reasons why this rescue helicopter disintegrated shortly after landing in the northern state of Para Wednesday.

An amateur photographer from the Para Fire Department showed how the aircraft came apart while vigorously vibrating.

One theory is the helicopter experienced what is known as "ground resonance"...which is what happens when the aircraft's rotor is working while the helicopter is on the ground.

There were some injuries, but none serious.

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