Put together the numbers that show them it will be profitable, and present them to the airport management and any overseeing governmental committee (County Council, Airport Commission, etc.). You'll have to examine construction costs, financing options, amortization and repayment, maintenance, etc., as well as obtaining commitments from potential tenants. This won't be easy, but it's been done in the past.. The biggest problem is that the FAA won't fund taxiways to T-hangars, which adds significantly to the initial construction costs. Another option is to contact a company which builds and rents hangars on contract to airports. The company leases land from the airport, then builds hangars at their expense and collects rent from tenants. One company which does that is Sky Harbor (http://skyharbourhangars.com/
). Another possibility is to be your own contractor, and put together a consortium of tenants to put up the money (or otherwise obtain external funding) for the project. Most airports are happy to work with someone who will simply lease the and and take care of everything else themselves, but recognize that the contractor is taking on all the financial risk, which is why companies like Sky Harbour won't go ahead without serious commitments from potential tenants.