Definition
A federal aviation regulation that governs the airworthiness responsibility for civil aircraft operations. Paragraph (a) prohibits any person from operating a civil aircraft unless it is in an airworthy condition. Paragraph (b) places direct responsibility on the pilot in command to determine whether the aircraft is in condition for safe flight, and requires the pilot in command to discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur.
Plain English
This rule says you cannot fly a civil aircraft unless it is safe and legal to fly, and it makes the pilot in command personally responsible for checking that before takeoff and for stopping the flight if something goes wrong with the aircraft.
Context Anchor
You encounter this rule during preflight planning, aircraft inspection, and any time a problem is found before or during a flight.
Derivation
CFR stands for Code of Federal Regulations, the official collection of U.S. federal rules. Part 91 contains the general operating and flight rules that apply to most civil flying. Section 91.7 is the specific rule within Part 91 dealing with civil aircraft airworthiness.
Why Pilots Care
Pilots bear direct legal responsibility for airworthiness decisions, which protects safety and avoids regulatory violations.
Grounding Statement
Before flight, the pilot looks at the actual condition of the airplane and decides whether it is fit to fly under the rules.
Intuition Check
Do not read this as only a maintenance rule. It is also a pilot responsibility rule: the pilot in command must decide whether the aircraft is airworthy before operating it and must stop if it becomes unairworthy.
Example Sentence 1
Under 14 CFR 91.7(b), the pilot in command is responsible for determining that the aircraft is in condition for safe flight before each departure.
Example Sentence 2
When an electrical issue appeared in flight, the pilot applied 14 CFR part 91, section 91.7(b) and returned to the airport.