A 266-foot experimental airship that is being constructed inside an enormous World War II-era blimp hangar in Tustin was damaged Monday when a portion of the structure's roof collapsed.
Falling wood from the roof struck the $35-million airship, a prototype being built under a government contract, and caused a blast of helium to be released, forcing the evacuation of the area. Officials with Worldwide Aeros Corp. said the damage to the airship is "repairable" but declined to be specific.
The blimp-like aircraft 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.
In Tustin, the site of the former Marine Corps Air Station Tustin, the project has brought new life to a hangar that was a home for blimps during World War II.
Crews working on the prototype reported hearing creaking from the ceiling of the 17-story hangar and got out before a 25-foot by 25-foot portion of the roof collapsed.
A beam of sunlight poured through the hole onto the deflated airship Monday afternoon as officials waited outside for building officials to say it was safe to enter.
A cause for the collapse has not been determined, said Matt West, Tustin's principal management analyst. There were no reports of injuries.
"The wood structure is 70 years old," West said. "The high winds we've been having could've been a contributing factor."
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.
The prototype inside the Tustin hangar is half the size of the final product, which is expected to be capable of carrying 66 tons. The company hopes to put out a fleet of 24 airships, including some that could carry up to 250 tons.
Orange County Supervisor Todd Spitzer, who was at the hangar Monday, said the roof collapse worried him because the county is slated to take over the structure.
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.
Small pieces of wood fell from the hangar last week, Spitzer said, and while the incident was reported to the federal government, he said no one came out to inspect the building.
Staff writer W.J. Hennigan contributed to this report