The FAA’s most recent change to AC 43-18 includes a new definition of the term “part” that will be of interest to everyone dealing with aviation parts.
The AC defines the term “part” to mean:
Part: For the purposes of this AC, is an article that could be produced under the provisions of 14 CFR part 21 and is eligible for installation on a certificated aircraft without further manufacturing processes.
NOTE:The definition of a part for the purposes of this AC would not include raw materials or repair segments being utilized for the repair or alteration of a part. (i.e., sheet metal stock, sealants, lubricants, raw forgings, or castings, billet material, etc.
The fact that the definition is limited to only this particular Advisory Circular is an important limit, but it is fairly normal for definitions like this to take on a life of their own. FAA employees will cut-and-paste this definition into other documents over time, and they will also rely on it, in the absence of any other guidance, when trying to decide what is – and what is not – a “part.” This means that the definition may ultimately affect PMA parts producers and other parties in the industry – not just repair stations that fabricate parts.
If the definition gets used outside of the context of this Advisory Circular, then it is possible that the definition may create problems, in that it is self-contradictory. The definition states that “an article that could be produced under the provisions of 14 C.F.R. part 21;” however the FAA has issued PMAs for sealants and lubricants, which are not “parts” according to the note.
AC 43-18 is the Advisory Circular that provides guidance for Fabrication of Aircraft Parts by Maintenance Personnel. The most recent change (change two) which added this new definition was issued on June 7, 2011.