Torn Canopy Sparks Design Flap : Convention Center: Engineers try to figure out why giant tent panel ripped to shreds during rainstorm.

Perplexed officials Friday pondered what caused a giant Teflon-coated panel stretching over part of the San Diego Convention Center to tear to shreds--causing a massive water leak--while engineers and architects scrambled to find a quick fix.

The panel, 25 feet wide and 330 feet long, began tearing apart at 1 p.m. during Thursday’s rainstorm, when 27-to-35 m.p.h. winds ripped a hole in the sail-like panel. The wind enlarged the tear until the panel broke loose.

A spokesman for the San Diego Unified Port District, which owns the Convention Center, said engineers Friday were still trying to determine what caused the panel to tear. On Thursday, a Convention Center spokesman had blamed the tear on an aluminum strut that was ripped from its mooring.

Los Angeles architect Arthur Erickson, who designed the center, said the panel was designed to withstand winds of up to 100 m.p.h. Erickson and Jon Duncan, vice president of Birdair, a Buffalo, N.Y. company that manufactured the sail, said they did not know what could have caused it to tear.

“This thing was very carefully engineered and tested up to 100 m.p.h. It was a wind-tunnel test subjected to gale force winds,” said Erickson. “It (reason for the tear) could have been in the fabrication. Really, it could have been anything.”

Erickson said the panel was made from a plastic neoprene that is fiber reinforced.

Port District officials summoned engineers and architects Friday to inspect the damaged panel and to advise them on repairs. The panel, which is longer than a football field, covers four huge ventilation holes on the center’s main tent roof, keeping rain out of the special-events area. Officials said the main roof was not damaged.

Convention Center spokeswoman Donna Alm said rain has been falling through the vent openings. But she said the rain is being channeled toward floor drains, and there has been no water damage.

The combined cost for the sail and Convention Center’s tent roof was $1.6 million, Alm said. She put the entire cost for the tent roof and the special-events area it covers at $6 million.

However, Port District spokesman Dan Wilkens said that Port District officials do not know how much repairs will cost.

“Right now our main concern is to begin short-term repairs to minimize any further damage from the rain. That should only be a matter of a day. As for the ultimate solution for permanent repairs, I don’t have a clue,” Wilkens said.

In a telephone interview from New York, Duncan said that Birdair had sent an engineer and two superintendents to San Diego to inspect the damaged sail. He said he was not sure what may have caused the sail to tear.

On Friday, Port District officials said the sail was covered by a 10-year warranty. Port District Director Don Nay said he does not believe the Port District will have to pay for the damaged sail.

Duncan said his company manufactured the panel, but added that “we built it to the design of specifications.”

Birdair has manufactured similar panels for other public facilities, but this is the first time a panel manufactured by the company has failed in 19 years, he added.

“We are just as interested to find out what caused the panel to fail as anybody else,” Duncan said.