Container No 1 is the US Federal Aviation Administration-manufactured "hardened" container, which was placed close to the cargo-hold wall where the fuselage is externally marked with the black grid lines. In each container, a "bomb" was placed against an outboard-facing wall to test for "worst-case" results. Immediate external visual inspection of the forward/left grid-painted area does not show any obvious deformation of the aircraft skin, but DERA's metallurgists will be examining all the relevant areas to determine the precise effects. Some port-side cabin windows have blown out, but the DERA remarks that such an effect when airborne would not threaten the aircraft's structure

The protective lining fixed against the cargo-bay wall next to a standard baggage container (No 2 in diagram) seems to have done its job well. Little or no fuselage deformation is visible in the area of the grid-marking, although some windows have blown out forward of it. DERA says that a "single fragment-hole" attributable to the explosion in No 2 has been found in the hull, within the grid, but that it would have caused no threat to the structure or to pressurisation in flight. DERA observes that greater protection could be obtained by lining the entire hold with the protective material tested here

The explosion in the standard-design container No 4 did serious damage. No protective hold-lining was used. The photographic sequence at the top shows the damage progression, starting (second frame) with a small hole emitting the flame of the explosion. Once ruptured, the fuselage begins to tear open under the combined blast-shock and cabin-pressurisation forces

Container No 3 is a "modified" standard container. The modification, says the CAA, consists of a 200mm-thick lining which does not have any special blast-attenuation qualities, but distances the explosion slightly from the container's outer wall and therefore from the fuselage skin. Distance, DERA experiments have shown, is a significant blast-attenuator. The grid area is clearly deformed but not significantly breached

Source: Flight International