Section 572.142 - Head assembly and test procedure(a) The head assembly (refer to § 572.140(a)(1)(i) ) for this test consists of the head (drawing 210-1000), adapter plate (drawing ATD 6259), accelerometer mounting block (drawing SA 572-S80), structural replacement of 1/2 mass of the neck load transducer (drawing TE-107-001), head mounting washer (drawing ATD 6262), one 1/2-20 * 1" flat head cap screw (FHCS) (drawing 9000150), and 3 accelerometers (drawing SA-572-S4).(b) When the head assembly in paragraph (a) of this section is dropped from a height of 376.0±1.0 mm (14.8±0.04 in) in accordance with paragraph (c) of this section, the peak resultant acceleration at the location of the accelerometers at the head CG shall not be less than 250 g or more than 280 g. The resultant acceleration versus time history curve shall be unimodal, and the oscillations occurring after the main pulse shall be less than 10 percent of the peak resultant acceleration. The lateral acceleration shall not exceed ±15 G (zero to peak).(c)Head test procedure. The test procedure for the head is as follows:(1) Soak the head assembly in a controlled environment at any temperature between 18.9 and 25.6 °C (66 and 78 °F) and at any relative humidity between 10 and 70 percent for at least four hours prior to a test.(2) Prior to the test, clean the impact surface of the head skin and the steel impact plate surface with isopropyl alcohol, trichlorethane, or an equivalent. Both impact surfaces must be clean and dry for testing.(3) Suspend the head assembly with its midsagittal plane in vertical orientation as shown in Figure P1 of this subpart. The lowest point on the forehead is 376.0 ±1.0 mm (14.76 ±0.04 in) from the steel impact surface. The 3.3 mm (0.13 in) diameter holes, located on either side of the dummy's head in transverse alignment with the CG, shall be used to ensure that the head transverse plane is level with respect to the impact surface.(4) Drop the head assembly from the specified height by a means that ensures a smooth, instant release onto a rigidly supported flat horizontal steel plate which is 50.8 mm (2 in) thick and 610 mm (24 in) square. The impact surface shall be clean, dry and have a finish of not less than 203.2 * 10-6 mm (8 micro inches) (RMS) and not more than 2032.0 * 10-6 mm (80 micro inches) (RMS).(5) Allow at least 2 hours between successive tests on the same head.