The Basics of Maintenance in General Aviation


Even the “pros” of our industry admit they need to be reminded from time to time of the basics of General Aviation maintenance. Therefore to review, the term maintenance means the inspection, overhaul, repair, upkeep and preservation of an aircraft and engine, including the replacement of parts, according to the FAA. The owner/operator is responsible for the proper maintenance of his aircraft and engine. The pilot in command of an airplane is responsible for:

  1. Determining whether the aircraft is in condition for safe flight.
  2. Having a Registration Certificate and a valid Airworthiness Certificate appropriately displayed in his aircraft during all operations.
  3. Having available in the aircraft an FAA-approved flight manual or operational limitations.
  4. Keeping abreast of current regulations concerning the operation and maintenance of his airplane and engine.


FAR 91.409 establishes minimum requirements pertaining to annual and 100-hour inspections. Not only does the FAA require these inspections, but they stipulate in FAR 91.405 that the owner/operator must maintain the airworthiness of the aircraft and engine during the time between the required inspections by having any airworthiness defects corrected and by ensuring that maintenance personnel make the proper entries in aircraft records approving the return to service. Although maintenance requirements will vary for different types of aircraft, the FAA states that experience shows most aircraft will need some type of preventive maintenance after every 25 hours of flying time and minor maintenance at least every 100 hours.

Annual Inspection

This inspection must be performed within the preceding 12 calendar months, by either a certified A&P mechanic holding an inspection authorization, an appropriately rated certified repair station or the manufacturer of the aircraft.

100-Hour Inspection

An aircraft used to carry passengers for hire, or for flight instruction for hire, must be inspected within each 100 hours of time in service by either a certified A&P mechanic, an appropriately rated certificated repair station or the manufacturer. The annual inspection is acceptable as a 100-hour inspection, but the reverse is not true.

Daily and Preflight Inspection

The owner or operator may conduct a daily inspection, if so desired, but the pilot must perform a satisfactory preflight inspection before flight in order to determine that the aircraft is airworthy

Airworthiness Directives

Airworthiness Directives, commonly referred to as “AD Notes,” provide aircraft owners with information of unsafe conditions. The ADs specify the aircraft or component found to be unsafe by the FAA, and the conditions, limitations or inspections, if any, under which the aircraft may continue to be operated.

The Federal Aviation Regulation requires a presentation showing the current status of applicable airworthiness directives, including the method of compliance, and the signature and certificate number of the mechanic or repair agency who complied with the AD.

It is the aircraft owner or operator’s mandatory responsibility to assure compliance with all pertinent AD notes. This includes those ADs of a recurrent or repetitive nature; for example, an AD may require a certain inspection every 100 hours. This means that the particular inspection shall be made and recorded after every 100 hours of flight time.

Manufacturer's Service Bulletins

The FAA states that whenever an aircraft or engine manufacturer determines, through service experience, that its product may be improved by some modification, or that the service life of its product may be extended by some particular maintenance or repair, that manufacturer may issue a service bulletin. The latter will tell what the trouble is and how to remedy it.

The service bulletin is mandatory because it supplements the manufacturer’s maintenance manual that is required by FARs. The service bulletin usually addresses those items that affect safety of flight. The Lycoming overhaul manual and all applicable service bulletins and service instructions, used in conjunction with the appropriate operator’s manuals, constitute the engine maintenance manual required by the FAA / FAR 43.13.

In addition to service bulletins, Lycoming also publishes service instructions and service letters. A service instruction is product information that also becomes a part of the manufacturer maintenance manual, and therefore compliance with these publications by owners and operators is required. The service letter at Lycoming is product information which can be optional to the pilot/owner.

Preventive Maintenance

Preventive maintenance means simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations. The holder of a pilot certificate issued under FAR 61 may perform preventive maintenance on any aircraft owned or operated by the pilot that is not used in air carrier service or air taxi. All other maintenance, repairs, rebuilding or alternations must be performed by persons authorized to do so by the FAA.

Except as noted under “Preventive Maintenance,” all repairs and alterations are classed as either Major or Minor. Major repairs or alterations must be approved and returned to service by an appropriately rated certified repair facility, an A&P mechanic holding an Inspection Authorization or a representative of the FAA. Minor repairs and alterations may be returned to service by an appropriately rated certified A&P mechanic or repair facility

Progressive Maintenance

This is a continuous maintenance program whereby the required FAA and manufacturer inspections are accomplished during the most convenient time, while keeping the aircraft in a state of continuous airworthiness.

Several General Aviation airframe manufacturers have established sound Progressive Maintenance programs with FAA approval. Owners and operators are reminded that certain FAA requirements must be met before a Progressive Maintenance program can be used. These requirements are contained in the Federal Aviation Regulations, Part 43, “Maintenance, Preventive Maintenance, Rebuilding and Alteration,” and Part 91.409, “General Operating and Flight Rules.”

The Progressive Maintenance program has had more appeal where planes for hire are involved (i.e., commuter, air taxi, flight instruction), rather than those privately owned.

Aircraft Flight Test After Repair or Alteration

The FAA reminds us that whenever a repair or alteration has been made to your aircraft or engine, the person authorized to return the aircraft to service should decide if the flight characteristics have changed or if operation in flight has been substantially affected. If the decision is affirmative, the aircraft must be flight tested before it may be used to carry passengers in accordance with FAR 91.407. The test pilot must make an operational check of the maintenance performed and log the flight and findings in the aircraft records.

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