Crash blamed on too
little analysis
NASA says the Helios, which
plummeted off Kauai, was not
suited for turbulence
Too little analysis, an inadequate risk assessment and an "inappropriate decision" led to the destruction of a $15 million unmanned aircraft over waters off Kauai more than a year ago, a NASA panel concluded in its final report, released yesterday.
The five-member panel said changes in the Helios flying wing from a model that set a world high-altitude record in 2001 made the aircraft unstable in turbulence that occurred off Kauai's leeward coast when it crashed on June 26, 2003.
The plane, built and operated by AeroVironment Inc. of Monrovia, Calif., fluctuated up and down, exceeding its design speed, before breaking up and crashing into the ocean, the investigation said.
The report concluded, "Lack of adequate analysis methods led to an inaccurate risk assessment of the effects of configuration changes leading to an inappropriate decision to fly an aircraft configuration highly sensitive to disturbances," the report said.
The panel said, however, that enough data is available on high-altitude, long-endurance flight to continue the program and conduct future successful flights.
"The mishap underscores our need to assess carefully our assumptions as we push the boundaries of our knowledge," Victor Lebacqz, NASA associate administrator, said in a news release.
The report did not blame anyone for the failure and said teams working with the aircraft had created "most of the world's knowledge" of high-altitude, long-endurance aircraft. It recommended several improvements in analysis, ground testing and technical oversight of the project, which has both military and civilian application.
The panel also suggested that NASA move more slowly, with incremental flight tests when major design changes are made in the aircraft.
Lebacqz said NASA would follow the board's recommendations "to help ensure the payoffs of such vehicles are fully realized."
The Helios that broke apart over the Pacific was a solar electric-powered flying wing designed to operate at high altitudes for very long flights. A differently configured model launched from Kauai set an altitude record in 2001 for non-rocket-powered fixed-wing aircraft of 96,500 feet.
The delicate plane, with a 247-foot wingspan and 10 propeller-driven engines, had been equipped with an advanced experimental fuel cell system that used solar power during the daytime and battery power at night.
Most of the aircraft was recovered for the investigation.
Eventually, NASA hopes to develop remote-controlled aircraft that can remain aloft for months at a time up to 100,000 feet above the earth without the need for refueling. The planes could boost civilian communications and military surveillance capabilities, offering a new wireless communications base between the world's highest antennas and satellites.
