The FAA issues Letters of Interpretation and Chief Counsel Opinions in order to clarify existing rules and regulations. Where these can be found and searched when looking for clarification of a rule?
The FAA Regulations Division maintains a webpage which includes a searchable database of "Legal Interpretations & Chief Counsel's Opinions". It includes the following disclaimer:
Legal Interpretations and the Chief Counsel's opinions are now available at this site. Please note that not all interpretations or Chief Counsel's opinions are available at this time. This database consists of legal interpretations issued from 1990 to the present and will be updated on a regular basis.
The letters can be searched by year and/or keyword.