Definition
Aircraft parts that change an aircraft from its original FAA-approved type design. Installation of modification parts requires FAA approval, typically through a Supplemental Type Certificate (STC), a field approval, or other approved data, to ensure the change still meets airworthiness standards.
Plain English
Parts that alter an aircraft from how it was originally built and certified. Because they change the approved design, the FAA must approve them before they can be installed and flown.
Context Anchor
Pilots may see this term in FAA material about aircraft approval, maintenance records, logbook entries, or equipment changes.
Derivation
Modification comes from a word meaning to change or adjust something. Parts are the physical pieces being installed. Together, modification parts means physical aircraft pieces used to change the airplane, not merely to restore it to the same condition.
Why Pilots Care
Using unapproved modification parts can make the aircraft unairworthy and lead to legal issues.
Intuition Check
Do not read modification parts as simply “parts that have been modified.” In this FAA context, it means parts used to modify the aircraft itself.
Example Sentence 1
Before installing the new landing light, the mechanic confirmed that the modification parts were covered by an approved STC.
Example Sentence 2
Before flying with modification parts, the pilot verified that the logbooks reflected the approved installation.