Aircraft Logbooks


Aircraft Logbook Responsibilities:

  • Aircraft owners/operators shall keep and maintain aircraft maintenance records per FAR 91
  • Each person who maintains, performs preventive maintenance, rebuilds, or alters an aircraft, airframe, aircraft engine, propeller, appliance, or component part shall make an entry in the maintenance record of that equipment
  • the person approving or disapproving for return to service an aircraft, airframe, aircraft engine, propeller, appliance, or component part after any inspection performed shall make an entry in the maintenance record of that equipment

Required Records:

  • Each owner or operator to ensure that maintenance personnel make appropriate entries in the maintenance records to indicate that the aircraft has been approved for return to service
    • Section 91.417(a) sets forth the content requirements and retention requirements for maintenance records
    • Maintenance records may be kept in any format that provides record continuity, includes required contents, lends itself to the addition of new entries, provides for signature entry, and is intelligible
    • Section 91.417(b) requires records of maintenance, alterations, and required or approved inspections to be retained until the work is repeated, superseded by other work, or for one year
    • Section 91.417(b) requires records to be retained and transferred with the aircraft at the time of sale
  • Separate or individual records are not required for each engine, propeller, rotor, and appliance of an aircraft
    • The information specified in 91.417(a)(1) through 91.417(a)(2)(vi) are required to be kept for each item as appropriate
    • As a practical matter, many owners and operators find it advantageous to keep separate or individual records since it facilitates transfer of the record with the item when ownership changes
  • Records are required to include "a description of the work performed"
    • The description should be in sufficient detail to permit a person unfamiliar with the work to understand what was done and the methods and procedures used
    • To provide for extensive work, the rule permits reference to technical data acceptable to the Administrator in lieu of making the detailed entry
    • Manufacturer's manuals, Service Letters (SL), bulletins, work orders, FAA ACs, and others, which accurately describe what was done or how it was done, may be referenced
    • Except for the documents mentioned that are in common usage, referenced documents are to be made a part of the maintenance records and retained
    • NOTE: Certificated Repair Stations (CRS) frequently work on components shipped to them without the maintenance records
      • To provide for this situation, repair stations should supply owners and operators with copies of work orders written for the work, in lieu of maintenance record entries
      • The work order copy must include the information required, be made a part of the maintenance record, and retained
  • Entries contain the date the work was completed, but in instances where one person conducted and another approved, there may be two dates
    • In this instance, there should be two signatures, however, only one is required

Maintenance Log Omissions:

  • Not all work may be logged, for example, that work done to correct a defect or mistake during manufacturing
    • In this case, Non-Conforming Material Reports (NCMRs) or like reports, document the work at the factory
    • These reports are not reflected in the aircraft logbooks as they occured in the factory, and everything prior to the issuance of an airworthiness certificate are proprietary
    • The result is potential differences from aircraft to aircraft and from maintenance manual to what is observed
  • When discrepancies are discovered during maintenance, the A&P must look into if the work is from a poor maintenance practice or a legitimate fix that is procedurally omitted from the logs


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