OK - surely though if you can not maintain a 'plane or any vehicle for that matter to a suitable standard - you don't use it. To do so if that is not case is criminal irresponsibility. Sanctions or not.
There were over 10,000 exceptions to the U.S sanctions against Iran (
With U.S. consent, companies skirt sanctions on Iran, others - The Denver Post) & I guess whilst aircraft parts would not be excepted it would be valid to find out if the sanctions in place would restrict Iran from obtaining parts necessary for the safe flight of civilian aircraft. i.e. Are they told they can not have or do they not ask?