Definition
A specific federal regulation that requires most U.S.-registered aircraft to have an annual inspection performed within the preceding 12 calendar months by an authorized person before the aircraft can be operated. The regulation also prohibits operating an aircraft unless it has received this inspection and been approved for return to service.
Plain English
This is the federal rule that says an aircraft must have a thorough inspection at least once every 12 months by a qualified mechanic, and it cannot be flown legally if that inspection is overdue.
Context Anchor
You will see this citation when checking aircraft maintenance records during preflight planning, especially when confirming that the annual inspection is still current.
Derivation
Title 14 of the Code of Federal Regulations is the section of U.S. federal law dealing with aeronautics and space. 'Part 91' covers general operating and flight rules. 'Section 91.409(a)' is a specific paragraph within that part. The numbering works like an address: Title 14 is the building, Part 91 is the floor, Section 91.409 is the room, and (a) is the specific shelf inside it.
Why Pilots Care
Confirms the aircraft meets legal airworthiness standards before flight and helps prevent operation with unresolved maintenance issues.
Analogy
Think of this citation like an address for a rule. “Title 14” is the neighborhood, “part 91” is the street, and “section 91.409(a)” is the exact house where the inspection rule lives.
Intuition Check
Do not read “part” or “section” as casual book words here. In this context, they are exact legal locations inside federal aviation rules.
Example Sentence 1
Before accepting the aircraft, the pilot checked the maintenance logbook to confirm the inspection required by 14 CFR part 91, section 91.409(a) had been completed within the last 12 calendar months.
Example Sentence 2
An examiner may ask about Title 14 of the Code of Federal Regulations (14 CFR) part 91, section 91.409(a) to ensure the aircraft has the required recent inspection before approving a flight.