A major US jet engine maker will investigate the effects of volcanic ash on the engines of aircraft that have flown through the plume.
Honeywell Aerospace's engines powered several of the planes sent up to collect scientific data after eruptions of the volcano in southern Iceland in April and May suspended European air travel.
The planes, which accumulated dozens of hours of flying in the clouds, were operated by Germany's national aeronautics research centre DLR and by the British weather service.
The two TPE331 turboprops that powered the German Dornier 228 had been returned to Phoenix, Arizona, where they would be disassembled and analysed in detail, Ronald Rich, vice president of propulsion systems at Honeywell, said.
The Honeywell investigation is believed to be the first such detailed analysis of engines affected by ash particles since the five-day closure of European airspace last month.
The unprecedented closure of European airspace because of a volcano caused direct losses of more than £900 million to the airlines affected, and as much as £1.3 billion to other businesses.
Few doubt that flying a plane directly into the plumes of a volcano could disable the aircraft. But it remains unclear whether the abrasive particles present a hazard to the jets outside the immediate area of the volcanic plume, once it is dispersed by high-altitude winds.
Over the past three decades, civil aviation has become increasingly aware of the dangers of flying through the microscopic fragments of rock and pumice that make up ash clouds.
Jet engines are highly complex machines designed to function in environments free of debris and corrosive gases, and the effects of volcanic ash have severely endangered safety on flights that directly overflew erupting volcanos. Inside the engines, the particles stick to the hot core and form a glasslike coating, grinding up turbines, bearings, and other moving parts. This can lead to the immediate loss of thrust and eventually to engine failure.
International regulators such as the International Civil Aviation organisation and the European Aviation Safety Agency have been trying to establish safe levels of particle contamination in the airspace.