Safety helmets go through many tests to ensure they are safe for use. Testing often occurs with a test helmet that's placed on a metal head form that can measure data.
Impact Tests
Impact tests measure a series of controlled impacts against a helmet. The tester drops the helmet multiple times onto different metals that simulate different kinds of impact surfaces. The head form measures g-force, or acceleration, as it falls. The faster the acceleration of the fall, the higher the g-force, posing greater risk of damage to the helmet. If it passes 300 Gs at any point, the helmet fails.
Stability Tests
The tester hooks a wire rope to the rear of the helmet with the free end extending over to the front. He drops a weight that creates a rotational load that pulls on the helmet. The tester then rotates the head form 180 degrees and secures the helmet, then repeats the test. The helmet may shift on the head form, but it must not come off.
Face Shield Tests
Face shields must withstand direct shots from a pellet rifle. The tester secures the helmet in a way that does not allow it to move, then he fires a soft lead pellet at approximately 310 mph. The pellet must not penetrate the face shield, and in the case of racing helmets, the indentation created on the inside of the face shield must not exceed 2.5 mm.
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