New and troubling questions are emerging about what caused last month's Air India crash in

Amdabad, which killed 260 people. A preliminary investigation released this weekend

ruled out mechanical or maintenance issues. The 15-page report found that the Boeing 787 Dreamliners

fuel cutoff switches, which stopped fuel from flowing to the

engines, had both been flipped in sequence just seconds after the plane took off and not long

before it crashed. Experts believe it's most likely that one of the pilots was responsible.

For more on this report, we are joined by our aviation correspondent, Miles O'Brien.

Miles, so good to see you.

Let's talk about those fuel switches and how they seem to have been shut off right after takeoff.

How do they work?

Is it possible that someone bumps it with their elbow and switches it off?

Is it possible there's some mechanical issue with those switches? What do we know about that?

Those switches, William, are designed to be readily available to the flight crew in the event that they need to cut off the fuel

because of, say, an engine fire. But because they need to be readily available and they're so

crucial, they are guarded in two ways. They are spring loaded. You have to pull up on the switch.

And then when you put it in place, it latches in place. So it's actually secured in two separate fashions.

It's, dare I say, impossible to just brush aside it and move that switch.

It's not something that can be done casually, and it points very strongly to deliberate intent.

In addition to that, William, there was no evidence of any sort of mechanical problem with the engines,

whether the engines might have failed in some fashion, and there was an incorrect procedure to restart the engines.

That was one of the early speculations.

But there's zero evidence that occurred.

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