49 C.F.R. § 572.182 – Head assembly.

(a) The head assembly consists of the head (drawing 175-1000), including the neck upper transducer structural replacement, and a set of three (3) accelerometers in conformance with specifications in § 572.189(b) and mounted as shown in drawing (175-0000 sheet 1 of 6). When tested to the test 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 per procedure specified in 49 CFR § 572.112(a).
(c) Performance criteria.
1. (1) When the head assembly is dropped in accordance with § 572.112 (a), the measured peak resultant acceleration shall be between 125 g's and 155 g's;
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 fore-and-aft component of the head acceleration shall not exceed 15 g's.