NEW ORLEANS (AP) -- The cause of a 34-minute blackout at the Super Bowl remains under investigation, but public records show that Superdome officials were worried about a power outage several months before the big game.

An Oct. 15 memo released Monday by the Louisiana Stadium & Exposition District, which oversees the Superdome, says tests on the dome's electrical feeders showed they had "some decay and a chance of failure."

The memo also says 2011 blackouts that struck Candlestick Park, where the San Francisco 49ers were playing a nationally televised Monday night football game, was one reason for ordering the tests.

The state board later authorized spending nearly $1 million on Superdome improvements, including more than $600,000 for upgrading the dome's electrical feeder cable system.

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