Maintenance Summary

  • Last updated on November 10, 2022

Regularly scheduled inspections and periodic adjustment and repair of aircraft.

Inspections and Repairs

Every aircraft registered in the United States must be maintained in accordance with Federal Aviation Regulations (FARs) to ensure continued airworthiness. This is accomplished through regularly scheduled inspections and periodic maintenance. The largest segment of American aviation is commonly called general aviation and includes thousands of privately owned aircraft as well as those operated for business purposes. General aviation aircraft range from two-seater trainers to fully equipped corporate jets and also include experimental, or homebuilt, aircraft.

All small aircraft of up to 12,500 pounds gross weight must undergo an annual inspection of the entire airframe structure, the power plant, and propeller, if so equipped, and all accessories and systems. FAR 43 lists the required scope and detail of the annual inspection and includes an approval statement to be written in the aircraft maintenance record, or logbook, which allows that aircraft to be operated for another year. Any necessary repairs must be completed before the inspector signs the approval.

In addition to the annual inspection, there is a required inspection for every one hundred hours of operation, if the aircraft is being used for hire. Rental aircraft, flight training, and all passenger-carrying revenue flights fall in this category. The one-hundred-hour inspection is performed to the same scope and detail as the annual inspection.

In Appendix A of FAR 43, maintenance is divided into three categories: major, minor, and preventive. Major repairs and alterations pertain to the integrity of the aircraft type design, or, the original configuration chosen by the manufacturer and approved by the Federal Aviation Administration (FAA). An authorized inspector must approve such repairs and alterations before returning the aircraft to service. Minor repairs and alterations may be performed and approved by a certificated airframe or power plant mechanic. A licensed pilot may perform preventive maintenance. All these maintenance actions must be entered in the appropriate aircraft and engine logbooks.

Large aircraft of more than 12,500 pounds gross weight are usually maintained under a program designed by the aircraft manufacturer and custom-tailored to suit the particular owner or operator’s needs. Each program is unique and must be reviewed and approved by the FAA.

The amount of time an aircraft is not available for use due to inspection and maintenance is known as downtime. To minimize downtime and maximize utility, an operator may place the aircraft in a progressive inspection program. Under the progressive inspection program, the entire aircraft is inspected during the course of a year, but the inspection itself is broken into several smaller segments at specified intervals. A typical progressive inspection program calls for inspection of the wings after one hundred hours of operation, the engine or engines at two hundred hours, the fuselage and tail section at three hundred hours, and the landing gear at four hundred hours, The cycle begins again with the wings at five hundred hours. Each progressive inspection program is designed for a specific operator using a specific aircraft and must be reviewed and approved by the FAA.

Maintenance Facilities

General aviation maintenance is usually performed by a fixed-base operator (FBO) at the local airport. The FBO may be a large, full-service complex offering fuel sales, aircraft rentals, flight instruction, engine overhauls, aircraft refurbishing, and charter flights. Some FBOs are one-person maintenance shops on private airstrips. An FBO may hold a Repair Station Certificate, issued by the FAA, that describes the types of specialized maintenance the FBO is equipped and qualified to perform. Repair stations are regulated under FARs 43 and 145 and may be certified to perform inspections, repairs, and maintenance on instruments, propellers, navigation and communication equipment, and accessory components, as well as on complete aircraft.

Many corporations have full-time flight and maintenance personnel to ensure aircraft availability and readiness. This advantage enhances the convenience of executive travel and provides additional support for corporate growth and development.

Airline Maintenance

Major air carriers are regulated under FAR 121 and usually operate large, transport-category jet aircraft. Their complex and detailed maintenance programs are designed by the aircraft manufacturer. They are tailored to each airline’s operational needs and must be separately approved by the FAA.

A typical airline maintenance program may include daily preflight inspections, weekly service checks, and periodic inspections, known as phase checks. Phase checks are usually lettered alphabetically, with each inspection being more detailed and occurring at longer intervals. An A-check may be scheduled every ninety days to check tires, fluid quantities, systems operation, and general aircraft conidition. A D-check, however, is a comprehensive inspection and overhaul of the complete airframe, engines, and accessories, along with electronics upgrades, corrosion control and subsequent repainting. This type of inspection and repair usually occurs about every five to six years and may take several months to complete.

Commuter airlines operate smaller aircraft to serve the outlying areas away from the major hubs of large cities and large airline activity. Commuter airlines are regulated under FAR 135 to operate and maintain less complicated aircraft without compromising safety. A commuter airline maintenance program is generally a progressive inspection and repair schedule designed to interface with that airline’s flight profile. It is usually based on the aircraft manufacturer’s maintenance manuals and must be approved by the FAA.

Military Maintenance

Military aviation is mission specific. Each type of military aircraft is designed for a particular task. Bombers, fighters, tankers, and trainers play exclusive roles in the overall military aviation effort. Such type division is reflected in military maintenance. Technicians are trained on a specific type of aircraft, on which they may continue to work for several years.

In addition, each aircraft is subdivided by system, such as engines, hydraulics, electrical, and fuel. A different team of trained specialists maintains each system. A crew chief, trained and experienced in several systems, is assigned to each aircraft, and serves as the maintenance coordinator for the specialist teams.

Maintenance Training

The privileges and limitations of aircraft mechanic ratings are listed in FAR 65. Each mechanic must perform maintenance operations in compliance with the regulation.

Maintenance Ratings

Airframe mechanics may inspect, repair, and maintain airframe structures, systems, and components according to the applicable manufacturers’ maintenance manuals. They may not repair instruments, navigation equipment, or communication equipment, and they may not approve major repairs and alterations as defined in FAR 43. They may, however, perform one-hundred-hour inspections on airframes and approve them for return to service after repairs.

Power plant mechanics may inspect, repair, and maintain engines, accessories, and propellers according to applicable manufacturers’ maintenance manuals. They may not approve major repairs and alterations, and they may not perform major repairs on propellers. They may, however, perform 100-hour inspections on power plants and approve them for return to service after repairs.

Most aircraft mechanics working in the general aviation maintenance industry hold both the airframe and power plant (A&P) ratings. Both ratings are granted indefinitely and are valid until surrendered, suspended, or revoked. Although not required by regulation in the aircraft manufacturing and major airline industries, the A&P ratings usually bring higher salaries and better job positions.

An employee of a FAR-145-certified repair station may qualify for a Repairman Certificate. This certificate is issued after the employee has been sufficiently trained and experienced in the particular maintenance tasks performed. Unlike Airframe and Power Plant Certificates, the Repairman Certificate is valid for the specified tasks only while the holder is in the employ of that particular repair station.

A Repairman Certificate may also be issued to the primary builder of an experimental, or homebuilt, aircraft. The repairman may then perform condition inspections on that aircraft. A condition inspection is similar to the annual inspection required on standard-category aircraft.

Aircraft mechanics holding both airframe and power plant ratings may also hold an inspection authorization. They may perform annual inspections of the entire aircraft and approve or disapprove it for return to service. They may also inspect any major repairs or alterations to the aircraft and approve it for return to service. Unlike Airframe and Power Plant Certificates, the Inspection Authorization must be renewed every year.

License Requirements

The requirements for the Airframe, Power Plant, and Repairman Certificates and for the Inspection Authorization are given in FAR 65. The regulation includes training and experience requirements, as well as written tests for subject knowledge and practical tests for demonstration of acquired skills.

There are two ways to obtain an A&P license: one must either graduate from an approved school or qualify through documented relevant experience. There are approximately 150 certificated aviation maintenance technician schools in the United States. Under FAR 147, these schools must provide a minimum of 1,900 hours of classroom instruction and shop experience. The FAA inspects these schools periodically to ensure regulatory compliance and to assist graduates in the certification process.

Aircraft maintenance personnel wishing to obtain A&P licenses may also present documented evidence of their work experience for FAA review and evaluation. The minimum requirements are eighteen months of full-time appropriate maintenance experience for either the airframe or the power plant rating or thirty months for both ratings together. Applicants may obtain their experience while serving in the military in selected job classifications or while being employed by a certified repair station, airline maintenance base, or aircraft modification facility. After reviewing and verifying the applicants’s documents and experience, the FAA issues permission for the applicant to take the written examination for the rating sought.

Testing Procedures

The written examination for the A&P license comprises three parts. The general test covers information that could apply to either airframe or power plant maintenance, such as regulations, publications, proper use of tools and equipment, aircraft hardware, and other related subjects. The airframe and power plant tests are subject-specific, as their names imply. The general test must be taken in conjunction with either of the other tests but is not repeated for the second rating.

After successful completion of the written examinations, the applicant schedules an appointment with the local designated mechanic examiner (DME). The DME is an experienced mechanic who has been appointed by the FAA to administer oral and practical examinations. The oral examination consists of a dialog between the examiner and the applicant to ascertain the applicant’s knowledge of aircraft maintenance theory and application. The practical examination is a series of maintenance tasks assigned to the applicant. The DME observes the applicant to evaluate the applicant’s use of technical data, mechanical skill, and proper procedures in performing the assigned tasks. Upon successful completion of the practical examination, the examiner issues a temporary mechanic certificate, that is immediately valid. The permanent certificate is mailed from the FAA registry within a few weeks.

The Airframe and Power Plant Certificates are issued for life and continue to be valid unless voluntarily surrendered by the mechanic or suspended or revoked by the FAA. The certificates, however, must be kept current by recent experience. FAR 65 requires that, in order to exercise the privileges of a mechanic certificate, the mechanic must have been actively engaged in aircraft maintenance for six of the preceding twenty-four months.

  • Kovach, Kenneth J. Corporate Aviation Management. 2d ed. Dubuque, Iowa: Kendall/Hunt, 1998. An overview of the corporate and business aviation industry, including history, management, flight and maintenance operations, and safety and security issues.
  • United States Department of Transportation. FAR/AMT 2000. Newcastle, Wash.: Aviation Supplies & Academics, 1999. Federal aviation regulations for the aviation maintenance technician.
  • Wanttaja, Ronald J. Airplane Ownership. New York: Tab Books, 1995. A digest of valuable information on all aspects of aircraft ownership, including annual inspections and owner maintenance procedures.
  • Welch, John F., ed. Van Sickle’s Modern Airmanship. 8th ed. Blue Ridge Summit, Pa.: Tab Books, 1998. A comprehensive reference book on current aviation technology, including flying techniques, performance standards, airframe structures, engine operation, and maintenance procedures.


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