Orange County Supervisor Todd Spitzer said Monday's partial roof collapse of an enormous World War II-era blimp hangar is the second incident in a week.
Small pieces of wood fell from the hangar last week, Spitzer said, and though the incident was reported to the federal government, he said no one came out to inspect the building.
On Monday, crews reported hearing creaking from the ceiling of the 17-story hangar and got out before a 25-by-25-foot portion of the roof collapsed.
Spitzer said the roof collapse worried him because the hangar and surrounding land is to be turned over to the county, which has been looking into converting it into a regional park.
"This is going to raise serious questions about the future of this hangar and whether Orange County can afford future liability," Spitzer said.
Spitzer said it costs about $1 million a year to maintain the hangar.
Falling wood from the roof struck the $35-million zeppelin, a prototype being built under a government contract. The damage caused a blast of helium to be released, forcing the evacuation of the area.
The 266-foot experimental airship is being built for the military to carry cargo to remote areas around the world, part of a resurgence in the production of blimps, zeppelins and spy balloons for everything from espionage to hauling supplies to isolated areas.
A cause for the collapse has not been determined, said Matt West, Tustin's principal management analyst. There were no reports of injuries.
About 650,000 cubic feet of helium was inside the airship when the roof collapsed, said Anatoliy Pasternak, vice president of production for Worldwide Aeros.
The airship, dubbed Aeroscraft, is made of aluminum and carbon fiber. Its builders say the craft is unlike other airships because it can control its weight and position by taking in and releasing air.