10 log10 (Tj) = 10 log10 (NF1E) + H+M+W +J+ Bj- 53 dB
10 log10 (Pi) = 10 log10 (T3) + Ki + 17 dB
for
N	Maximum number of closely spaced guns firing together. For guns that are dispersed on the host aircraft, such as in wing roots and in gun pods, separate vibration gunfire test spectra are determined for each gun location. The vibration levels, for test purposes, are selected for the gun that produces the maximum vibration levels.
E	Blast energy of gun (see Table 519.8C-III).
H	Effect of gun standoff distance, h (see Figure 519.8C-4).
M	Effect of gun location M = 0 unless a plane normal to the axis of the gun barrel and located at the muzzle of the gun does not intersect the aircraft structure, then M = -6 dB.
W	Effect of weight of the equipment to be tested (use Figure 519.8C-5). If the weight of the materiel is unknown, use W = 4.5 kilograms (10 lbs).
J	Effect of the materiel's location relative to air vehicle's skin (use Figures 519.8C-2 and 519.8C-6).
Bj	Effect of vector distance from the gun muzzle to the materiel location (see Figure 519.8C-7).
F1	Gunfiring rate where F1 = fundamental frequency from Table 519.8C-II (F2 = 2F1, F3 = 3F1, F4 = 4F1)
Tj	Test level in g2/Hz
Pi	Test level for frequency Fi in g2/Hz (where i = 1 to 4)
Ki	Effect of vector distance on each vibration peak, Pi (see Figure 519.8C-8).