What happened
On June 12, 2011, an American Blimp Corporation A-60+ blimp was conducting promotional sightseeing flights at Reichelsheim airfield. During its eighth flight of the day, the aircraft was transporting the pilot and three passengers to Bad Homburg for aerial photography.
As the pilot attempted to land at the Reichelsheim mooring site, the aircraft experienced a very heavy touchdown. Passengers reported a violent impact and immediately noticed the smell of fuel and heat emanating from the rear of the gondola. While the three passengers managed to evacuate the gondola, the pilot remained at his station.
Following the initial contact, the aircraft' and gondola began to slide along the ground. The fire spread rapidly through the gondola and ignited the outer envelope. Despite the weight loss from the passengers exiting, the buoyant force of the helium caused the burning airship to rise to an altitude of approximately 100 meters. The structure eventually failed, and the burning wreckage crashed about 400 meters from the initial impact site, where it burned completely. The pilot was recovered from the debris, but was deceased.
The investigation
The BFU examined the wreckage, including the landing gear components and the fuel system. Investigators analyzed the flight logs, which indicated the aircraft was heavily loaded with 15 ballast bags, making the landing conditions exceptionally difficult. The investigation focused on the mechanical failure of the landing gear and the subsequent breach of the fuel lines near the gascolator (water separator). Physical evidence showed that the landing gear strut had broken and became entangled in the rear of the airship.
Findings
- The primary cause of the accident was a landing gear failure during a hard landing, which caused the aircraft to strike the ground without its gear.
- The impact and subsequent sliding of the gondola caused the fuel drain hose to be pulled or displaced, leading to a significant leak from the gascolator.
- The leaking fuel was ignited by an electrical arc, likely caused by damaged wiring or contact with the broken landing gear strut.
- The heavy loading of the aircraft and the specific wind conditions contributed to the difficulty of the landing and the severity of the impact.
- The rapid spread of the fire was driven by the intense heat of the burning fuel, which quickly reached the flashpoint of the gondola's materials.