What is the purpose of an Advisory Circular??

Question

Looking for the general purpose of an AC. Regulatory or not? Where do they come from? Why not just change the FARs?

Answer 1

An AC is issued when there is a safety issue present, but there is not enough information to warrant passing an AD or regulatory change. The cost of an AD can be prohibitive to owners/operators. They need to let those people know that own/operate the aircraft effected that they should read the AC for what it is worth... almost as a warning to pay heed to the problem at hand.

The FAA is not going to force compliance on many issues that may or may not have been validated, so they atleast let you know that a possible trend has developed, and if it involves a part or aircraft that you operate, it would be in your best interest to inspect and investigate. Later if the trend continues, and more examples are found, then the FAA/DOT/NTSB will become obligated to say that it is more than coincidence, and make an official correction mandatory.

Answer 2

The FARs are regulatory... you have to follow them.  Advisory Circulars are more guidance.  Many of the regulations in the FARs are very vague.  ACs give pilots (and aircraft & equipment manufacturers) guidance on how to meet the FARs.  They show one way to meet the applicable FAR(s), but not the only way.  In fact, most ACs say something like that in the beginning of them.

Answer 3

they are not regulatory like AD notes but they are safety related.