What this is basically saying is Newcastles debt needs to be refinanced in the future (either extending terms with existing banks or go to new banks to pay off the existing ones). But like everyone at the moment deals on loans/mortgages/finance are not as good as they once were.
Therefore as part owners the councils might have to put some more money into paying for the future debt.
I dont think it helps that the newspaper article is talking about "bailing out".
In addition i dont think Newcastle airport will find it difficult to strike a deal on its debt.
The only thing that slightly concerns if its true is the value of the debt at £300M which appears on the face of it to be a lot for an airport the size of Newcastle.
But overall its stating what everyone knows, debt finance is more costly now, but I cant see there is much to worry about for the future of Newcastle.