Definition
To make an approved change to the design, configuration, or specification of an aircraft, engine, propeller, appliance, or component. In aviation maintenance, a modification alters the original type design and must be performed under FAA-approved data, such as a Supplemental Type Certificate (STC), an FAA Form 337, or manufacturer-issued service instructions.
Plain English
To officially change something on an aircraft from how it was originally built or approved, using paperwork and procedures the FAA accepts.
Context Anchor
Seen in aircraft maintenance, equipment installation, repair records, and discussions about changes to an aircraft or its parts.
Derivation
From the Latin modificare, meaning 'to limit, regulate, or set bounds.' In aviation the word kept the sense of a controlled, deliberate change — not a casual tweak, but a regulated alteration recorded and approved.
Why Pilots Care
Any modification can affect airworthiness, handling qualities, or required equipment; improper or undocumented changes can ground the aircraft or void insurance.
Intuition Check
Do not assume modify just means “make a small change.” In aviation, even a small modification can matter if it changes the aircraft from its approved original condition.
Example Sentence 1
The owner chose to modify the aircraft with an STC-approved auxiliary fuel tank to extend its range.
Example Sentence 2
All modifications must be entered in the aircraft logbooks with the appropriate sign-off before the next flight.