Aircraft maintenance checks are periodic inspections that every commercial and civil aircraft must go through after a certain number of flying hours or length of time of use. Military aircraft go through different sets of checks, but their maintenance programs are just as stringent.

The aviation industry is extremely regulated, and commercial operators must comply with the continuous inspection programs established by the aviation authorities of different countries. The Federal Aviation Administration of the United States, Transport Canada, and the European Aviation Safety Agency are several of these regulators. Each operator must establish a CAMP, or Continuous Airworthiness Maintenance Program, which includes routine and detailed inspections of air assets.

Commercial operators, airworthiness authorities, and MRO (maintenance, repair, overhaul) providers call detailed inspections “checks.” A and B checks are relatively minor, while C and D checks are more exhaustive. Aircraft operators can conduct lighter checks at their own facilities, but heavier checks must be performed by a certified MRO company.

A checks are performed every 400-600 flight hours, or 200-300 cycles (a cycle is one takeoff and landing). A checks last roughly 50-70 man hours and require an aircraft to remain on the ground for at least ten hours depending on the condition of the aircraft.

B checks, meanwhile, are performed every six to eight months and require 160-180 man-hours, depending on the aircraft type and condition. These checks often take one to three days.

C checks are performed every 20-24 months, or after a number of aircraft manufacturer defined flight hours. C checks are more extensive than A and B checks, and involve inspecting a large number of components. A C check will require an aircraft to stay in the maintenance site for at least two weeks, and will take up to 6,000 man-hours of work to finish.

D checks are the most comprehensive, invasive, and time-consuming check. Also called a heavy maintenance visit, D checks are performed roughly every six to ten years, and  go as far as taking the entire aircraft apart for inspection and repair. A D check can take up to two months, require 50,000 man hours of work, and cost one million dollars to complete. Most operators will choose to retire their aircraft after two or three D checks rather than go through another, as the cost of repair will actually exceed the value of the aircraft.

At ASAP Aviation Unlimited, owned and operated by ASAP Semiconductor, we can help you find all the aircraft repair parts and maintenance tools for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at 1-919-348-4040.

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Whether you are just entering the world of aviation or are a seasoned veteran in the industry, there is an entire library of terminology that you must be familiar with in order to succeed in this field. For those already acquainted with the industry, consider this an important review. And for those fledgling pilots, pilot mechanics and the like: get your study hat on and get to work.

Index of Terms

Absolute Altitude: height distance above ground level

Airline Transport Pilot (ATP): ATP refers to the pilot certificate necessary for anyone wanting to work for major and commuter airlines, as well as regional carriers. This certificate is meant to distinguish pilots with the highest level of experience. In order to obtain this certificate, you would need to complete a flight assessment and written test and would also need to have a minimum of 1500 hours of flight experience.

Airfoil: The basic structure of a wing, this refers to a surface with a carved top and a flat bottom

Axes of Flight: Refers to the three axis of flights which are 1) pitch, 2) yaw, and 3) roll. See definitions below.

Bernoulli Principle: A very important fundamental truth in flight, this principle was published in 1738 by Swiss scientist Daniel Bernoulli. In his book Hydrodynamica, Bernoulli explains how lift can be generated via air pressure over an airfoil. The curved top of the airfoil cuts the natural flow of air, increasing air pressure below the wing and lowering pressure above. This, in turn causes the aircraft to lift.

Federal Aviation Administration (FAA): the official United States national authority responsible for regulating all aspects of aviation in the US including air traffic management, construction and operation of airports, operation and construction of US airports, etc.

Federal Aviation Regulation (FAR): the official rules outlined by the FAA which regulate all aviation activities in the US including flights, pilot training, drone operations etc.

International Air Transport Association (IATA): a trade association that consists of 290 of the world’s airlines, with primary major carriers from 117 countries

Knots: refers to nautical miles per hour (100 knots is equivalent to flying 115 MPH)

Nautical Mile: used to measure aviation distance (one nautical mile is equal to 1.15 standard U.S. miles)

Pitch: one of the three axis of flights, refers to the axis which is perpendicular to the yaw axis. It is also parallel to the wing plane and located towards the right wing tip

Roll: one of the three axis of flights, perpendicular to the pitch and yaw axis, directed towards nose of aircraft

Slipstream: stream of air that is created by either a rotor or generator

Transponder: A device for transmitting and responding details on an aircraft’s position and altitude. Transponders are used to provide alerts of aircraft to air traffic controllers; useful for averting on air collisions

Yaw: one of the three axis of flights that is directed toward the bottom of the aircraft, and perpendicular to the plane of the wing with its origin at the center of gravity

These are just a few selections of important aviation terms but there are many more terms that are needed to understand aviation. You can trust that experts in the industry, such as the professionals at ASAP Aviation Unlimited, will understand these terms and know how they apply in the field. For any such questions you might have on important military parts, NSN parts or CAGE Codes, feel free to consult us by calling +1-919-348-4040 or emailing us at

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