Typically, large infrstructure projects require hefty loans to pay for the land purchase and construction. Banks will generally require various covenants to ensure the capacity of the project company to pay the interest on the debt - typically one finds in project budgets that the affordability gap is tightest immediately after construction is complete and revenues just start coming on line.
Spain is receiving a bail-out to help save its banks - it is likely that commercial and state owned banks will have very little leeway to let debts just keep on piling up somewhere. In addition, there will be political pressure to ensure banks are seen to correctly classify non-performing loans as being in default, sell of the loans to a Govt-owned bad bank, at which point private investors will have sufficient confidence to inject fresh capital into banks, the banking sector returns to health, credit is available to Spanish companies and the Spanish economy can be revived.
Somebody somewhere will be asking whether any more money can be committed to Corvera as a project or whether the money taps will be turned off for good and "alternative measures" similiar to those at Ciudad Real need to be taken by the board of the Corvera airport company.