Definition
Permanent maintenance records kept for each engine installed on an aircraft, documenting total time in service, inspections performed, repairs, overhauls, replacement of life-limited parts, airworthiness directive (AD) compliance, and any other actions affecting the engine's airworthiness. Engine logbooks are required by 14 CFR Part 91 and are maintained separately from the airframe logbook so that the engine's history travels with the engine if it is removed and installed on another aircraft.
Plain English
A written history book for the airplane's engine. It records every inspection, repair, and overhaul the engine has had, plus how many hours it has run. The pilot checks it during preflight to make sure the engine is legal and safe to fly.
Context Anchor
A pilot may review engine logbooks during preflight planning, before renting or buying an airplane, or when checking whether required maintenance has been completed.
Derivation
From the old ship's 'log' — a record of a vessel's voyages and condition. Aviation borrowed the term directly: the engine logbook is the engine's voyage record, tracking its life from new through every inspection and repair.
Why Pilots Care
A pilot must verify the engine logbooks are current and complete before flight; missing or inaccurate entries can ground the aircraft and affect its legal airworthiness.
Intuition Check
Do not think of engine logbooks as a pilot’s personal notebook. In this context, they are official maintenance records for the engine, not casual notes about flights.
Example Sentence 1
Before accepting the rental, she reviewed the engine logbooks to confirm the 100-hour inspection was current.
Example Sentence 2
After the oil change, the mechanic recorded the work and total engine time in the engine logbooks.