I'm not aware of any interest-free student loans available in Canada. In Ontario, some aviation programs at the university, community college or private level can qualify for Ontario Student Assistance Program (OSAP) loans, scholarships and bursaries. I'm sure similar government loan programs are available to students in other provinces.
There are a few schools in Canada that are fully subsidized, in which students are responsible for a normally priced college tuition (3-4K per year) and the government covers the flight training expense. There's even a CEGEP school in Quebec (similar to college) that offers CPL training at virtually no cost to the student.
These are the four schools that I'm aware of that offer government subsidized training:
Confederation College (ON)
Sault Ste Marie (ON)
Seneca (ON)
CEGEP Chicoutimi (QC)