(I believe this is the first time the German Commission report has been made available to the public on the internet.)
The German Commission determined that the most probable cause of the accident was a hydrogen leak in gas cell 4 or 5 in the rear of the ship, perhaps through the tearing of a wire, through which hydrogen entered the space between the cells and the outer cover.
The Commission believed the hydrogen-air mixture was most probably ignited by a spark between the ship’s outer cover and its framework, created as a result of the differing electrical charge between the ship and the ground:
“After dropping of the landing ropes, the surface of the airship’s outer cover became less well grounded than the framework of the airship due to the lower conductivity of the outer cover fabric. At rapid changes of the atmospheric field, which are the rule during night thunderstorms and have also to be assumed in this present case, electric potential differences occurred between spots of the ship’s exterior and the framework. In case these spots were sufficiently moist, which was especially probable in the region of cell 4 and 5 in consequence of the previous passage through a rain area, those differences could lead to equalization of tension by a spark, which possibly caused ignition of a hydrogen-air mixture present over the gas cells 4 or 5.”
For a discussion of the discredited theory that the ship’s fabric covering rather than its hydrogen gas was the primary cause of the disaster, visit: