49 C.F.R. § 572.192 – Head assembly.

(a) The head assembly consists of the head (180-1000) and a set of three (3) accelerometers in conformance with specifications in 49 CFR 572.200(d) and mounted as shown in drawing 180-0000 sheet 2 of 5. When tested to the procedure specified in paragraph (b) of this section, the head assembly shall meet performance requirements specified in paragraph (c) of this section.
(b) Test procedure. The head shall be tested according to the procedure specified in 49 CFR 572.112(a).
(c) Performance criteria.
1. (1) When the head assembly is dropped from either the right or left lateral incline orientations in accordance with procedure in § 572.112(a), the measured peak resultant acceleration shall be between 115 g and 137 g;
2. (2) The resultant acceleration-time curve shall be unimodal to the extent that oscillations occurring after the main acceleration pulse shall not exceed 15% (zero to peak) of the main pulse;
3. (3) The longitudinal acceleration vector (anterior-posterior direction) shall not exceed 15 g.