Sec. 7. A political subdivision may incur debt that exceeds the maximum amount allowed under section 6 of this chapter as necessary for the public protection and defense only:
(1) in time of war, foreign invasion, or other great public calamity; and
(2) upon petition of a majority of the property owners in number and value within the limits of the political subdivision.
The amount of the excess may not be greater than the amount specified in the petition.