General (ICAO)

ICAO Annex 6 Part II (International General Aviation) §2.4.6 and ICAO Annex 8 require that records of operating time, maintenance and modifications be kept for each aircraft — collectively the aircraft logbook(s) or separate records.

Purpose:

Evidence of continuing airworthiness through a complete operations and maintenance history,
Tracking of defects and their rectification,
Basis for ARC renewal and next scheduled inspections,
On aircraft sale: value proof and audit trail.

Typical components (named differently by State):

Flight log — per flight: date, pilot, departure/arrival aerodrome, off-block/on-block times, block time, flight time, landings, remarks, pilot signature.
Aircraft log / maintenance log — maintenance events, inspections, modifications, repairs, component changes.
Engine log — one per engine.
Propeller log — one per propeller.
APU log (if installed).

Europe (EASA / EU)

Regulation (EU) 1321/2014 Part-M.A.305 / Part-ML.A.305 (Continuing Airworthiness Record System):

For private ELA1 aircraft (Part-ML), the logbooks are: Aircraft Logbook, Engine Logbook(s), Propeller Logbook.
Records must be retained for 24 months after the aircraft has been permanently withdrawn from service.
On sale: all records are transferred to the buyer.

Part-M.A.305(d)/(e) content:

Total and current flight and operating time of aircraft, engine, propeller,
All maintenance and inspections with date, person performing the work and release statement,
Airworthiness Directives (ADs) and Service Bulletins (SBs) complied with,
Modifications and repairs,
Defects and their rectification (snag tracking),
ARC and its renewals.

PIC obligation: After each flight, enter and sign the logbook entries (block/flight times, any defects) — Part-NCO.GEN.150(b).

Germany (national)

Logbook obligation: §13 LuftBO / §3 LuftPersV require the carriage and maintenance of logbooks in accordance with Part-M/Part-ML.

Format: no mandatory layout; commonly used formats:

Maintenance logbook per Part-ML/M: often in printed form (e.g. "LBA-Form 1") or digital (approved software).
Flight log for each flight.

Storage: originals with the owner; the maintenance organisation may make copies.