TurboTax probably has a dedicated function for PDF export, so it should be no problem to convert TAX2011 forms to PDF format using it. You could achieve the same with virtual PDF printer and simply printing the form to PDF.
Convert TurboTax 2011 tax return file to Adobe Portable document format.
We have found 2 software records in our database eligible for .tax2011 to .pdf file format conversion.
Microsoft Windows software - convert tax2011 to pdf on Windows
A tax preparation software developed by Intuit
Convert from tax2011 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned tax2011 to pdf. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert tax2011 to pdf on OS X
Popular tax preparation software