Pershing II motor fire in Heilbronn (Januar 11th, 1985): Sequence of events as PII first stage motor was being removed from its shipping container which led to the motor fire and damage. Figure 2a shows a positively charged patch on the outer surface of the composite PII motor case created by the silicone foam rubber cradle pads of the container. An external arc discharge resulting in the internal arc is shown in 2b. Figures 2c and 2d show the progressive expansion of the localized high pressure area causing case failure which resulted in the collapse of the grain, shown in 2e, and the separation of the nozzle/aft skirt section. Figure 2f shows the result of the high pressure pocket formed in the "P-groove" area in the front of the propellant grain.
James A. Knaur
<a rel="nofollow" class="external text" href="http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADP005343&amp;Location=U2&amp;doc=GetTRDoc.pdf">Technical Investigation of 11 January 1985 PERSHING II Motor Fire</a>, page 7