Author Description

Neck injury risk can increase when aircrew wear head mounted equipment while exposed to +Gz loads. The effects of added weight and change in center of gravity (CG) were determined during a centrifuge study using an instrumented manikin at Brooks Air Force Base, Texas. Data included centrifuge Gz, head acceleration (three axes), head and C7-T1 pitch moment, and compressive and shear forces. Helicopter (0.5 G/sec at +1.75 and +4 Gz) and tactical aircraft (2 and 6 G/sec from +4 to 12 Gz) accelerations were simulated (5 sec plateau at each level). Effect of added weights (up to overall 2.7 kg) was measured in the forward pitch and lateral planes and tested using ANOVA. Seven real helmet systems were also tested. Head Gx and Gy increased with increasing +Gz load, head weight, as CG shifted in the forward pitch plane, and onset rate. Head Ox was greatest when weight was distributed laterally. The resultant head and neck force and moment increased with increasing weight, pitch angle, and +Gz load. Neck forces and moments were significantly larger than those measured in the head.