Section 92. Real estate tax for debt service

If a city issues its
  obligations for any project or to raise  funds  to  loan  in  aid  of  a
  project,  such  city  may  levy  an ad valorem tax on real estate to the
  extent that revenues derived in any year from taxes levied  pursuant  to
  this  chapter, together with revenues from the project or projects aided
  by the proceeds of any such obligations  shall  become  insufficient  to
  provide  fully  for  the  payment of principal and interest in that year
  upon obligations issued for either or both purposes.