Hindenburg Disaster - Fire's Initial Fuel - Hydrogen Hypothesis - Puncture Hypothesis

Puncture Hypothesis

One hypothesis on how gas could have leaked is that one of the many bracing wires within the airship snapped and punctured at least one of the internal gas cells during one of the sharp turns in the landing maneuver. Advocates of this hypothesis believe that the hydrogen began to leak approximately five minutes before the fire. Newsreels as well as the account of the landing approach show the Hindenburg made several sharp turns, first towards port and then starboard, just before the accident. Gauges found in the wreckage showed the tension of the wires was much too high, and some of the bracing wires may have even been substandard. One bracing wire tested after the crash broke at a mere 70% of its rated load. A punctured cell would have freed hydrogen into the air and could have been ignited by a static discharge (see above), or it is also possible that the broken bracing wire struck a girder causing sparks to ignite hydrogen.

A ground crew member, R.H. Ward, reported seeing a piece of the airship fluttering, "as if gas was rising and escaping" from the cell. He said that the fire began there, but that no other disturbance occurred at the time when the fabric fluttered. Another man on the top of the mooring mast had also reported seeing a flutter in the fabric as well. When the fire started, people on board the airship reported hearing a muffled sound, and another ground crew member on the starboard side reported hearing a crack. Some speculate the sound was from a bracing wire snapping.

Dr. Eckener concluded that the puncture hypothesis was the most likely explanation for the disaster. Because of this, he felt that Captains Pruss and Lehmann, and Charles Rosendahl were to blame for rushing the landing procedure. He believed that Lehmann told Pruss to make the sharp turn, and that Pruss and Rosendahl were concerned more about the time delay than the weather, because an unobserved storm front occurred just when the Hindenburg approached. But Eckener knew that he was to blame as much as anyone else; in 1928 he declined an offer for helium by the US Government for economic reasons.

Concluding the United States Inquiry on the disaster, Eckener testified that he believed that the fire was caused by the ignition of hydrogen by a static spark:

I believe that the fire was not caused by an electrical spark, but by a static spark. A thunderstorm front had passed before the landing maneuver. However if one observes more closely one can see that this was followed by a smaller storm front. This created conditions suitable for static sparks to occur. I believe spark had ignited gas in the rear of the ship.

It may seem strange that the fire did not occur the moment the landing ropes had touched the ground, because that is when the airship would have been earthed. I believe there is an explanation for this. When the ropes were first dropped they were very dry, and poor conductors. Slowly however they got dampened by the rain that was falling and the charge was slowly equalized. Thus the potential difference between the airship and the overlying air masses would have been sufficient enough to generate static electricity. The Hindenburg would have acted as a giant kite, close to the storm clouds, collecting a static spark.

I am convinced that a leak must have occurred in the upper rear section of the ship. My assumption is confirmed by the remarkable observations by one of the witnesses. He described seeing a peculiar flutter as if gas were rising and escaping. If I were to be asked to explain what had caused this abnormal build-up of gas, I could only make to myself one explanation.

The ship proceeded in a sharp turn during its landing maneuver. This would have generated extremely high tension in the sections close to the stabilizing fins, which are braced by shear wires. I suspect that under such tension one of these wires may have broken and caused a rip in one of the gas cells. The gas then filled up the space between the cell and the outer cover, which is why the airship sank at the rear. This accumulated amount of gas was then ignited by a static spark. This was not lightning but a small static spark, enough to ignite free gas in the rear.