Definition
An FAA Advisory Circular titled 'Acceptable Methods, Techniques, and Practices — Aircraft Alterations.' It provides FAA-accepted guidance for performing alterations to civil aircraft when no manufacturer or other approved data is available. It is the companion document to AC 43.13-1, which covers repairs rather than alterations.
Plain English
An FAA guidance booklet that tells mechanics how to make changes to an aircraft the right way when the manufacturer hasn't provided specific instructions for that change.
Context Anchor
Seen in aircraft maintenance records, alteration paperwork, mechanic discussions, and references to FAA-accepted repair or alteration methods.
Derivation
Advisory Circular' means a non-regulatory document the FAA issues to advise the aviation community on how to comply with the rules. The number '43.13-2' points to Title 14 of the Code of Federal Regulations, Part 43 (Maintenance), Section 13, second document in the series. Knowing this helps you see it isn't a regulation itself — it's accepted guidance that supports Part 43.
Why Pilots Care
When an alteration is performed using AC 43.13-2 methods and no other approved data exists, the FAA accepts those methods as a basis for return to service. Pilots who own or operate aircraft should know their mechanic is working from approved or accepted data — this is one of the standard sources.
Intuition Check
Do not read Ac 43.13-2 as a regulation by itself. It is FAA guidance that may be used as an accepted method when the situation fits and no more specific instructions apply.
Example Sentence 1
The mechanic referenced AC 43.13-2 when installing the supplemental fuel tank because the STC didn't specify the bonding procedure.
Example Sentence 2
Following Ac 43.13-2 kept the alteration within FAA guidelines.