A leaky hydraulic system, incomplete records and a dead battery all became part of the Deepwater Horizon story as a House investigative subcommittee revealed new details about the oil-rig explosion that set off the massive spill in the Gulf of Mexico.
Lawmakers zeroed in on the Deepwater Horizon's blowout preventer, a huge assembly of metal, hydraulics and wiring that's supposed to stop a blowout when it happens, if not sooner.
The device is on the floor of the Gulf, where some 4 million gallons of oil have leaked out since the April 20 accident that killed 11 people.
Both the rig and the blowout preventer are owned by Transocean Ltd.
Transocean CEO Steve Newman tried to explain one of the blowout preventer's problems to Rep. Jan Schakowsky (D-IL).
The problem: One of its hydraulic rams had mistakenly been replaced by a piece of test equipment, rendering the ram useless. He said that in such a situation, it won't serve to restrict or seal off the flow of hydrocarbons from the well.
"So in that case ... would that be a mistake?" Schakowsky asked.
"It would be a mistake to rely on that in a well-control situation, yes," Newman replied.
The blowout preventer had other problems, too.
The controls for a device called a dead man's switch that might have activated the blowout preventer were connected to a dead battery.
There's also evidence that the ultimate preventer, the blind-shear ram, may not have been strong enough to cut through both the well pipe and a drill pipe.
Engineers sent robots down after the accident to try to activate it. They didn't get very far.
"We found leaking hoses, and, you know, the diagrams that we were using real-time did not match the blowout preventer," said Lamar McKay, chairman of BP America, which leased the rig from Transocean.
Lawmakers pressed the oil industry executives on other suspected problems. One was the cement-and-pipe structure within the well.
Rep. Henry Waxman (D-CA) noted that one test showed nothing would leak out of the well. But another test, about possible leaks of oil and gas into the well, wasn't so definitive.
"What significance does that have?" Waxman asked Newman, the Transocean chief.
"The significance of the discrepancy between the two pressures would lead to a conclusion that there was something happening in the well bore that shouldn't be happening," he said.
Rep. Ed Markey (D-MA) said BP wildly exaggerated its ability to clean up an oil spill. But McKay defended his company's commitment.
"We're doing everything we can," he said. "I believe that we will learn things through this, there's no doubt. And I believe that those certifications will be with the knowledge that we have."
Republicans on the panel struck a different tone. They don't want the Deepwater Horizon to become a symbol of what's wrong with fossil fuels.
"To use this as the equivalent of the Three Mile Island accident for nuclear power and set back domestic oil and gas production on the outer continental shelf for the next 20 or 30 years -- that would not only be a mistake, in my opinion, it would be a disservice to the American people," Texas Republican Rep. Joe Barton said.
He said the well that's leaking is considered capable of producing 50,000 barrels of oil a day once it's under control.