What are the Necessary Inspections for Aircraft Maintenance?

Aircraft inspections are a crucial element of aircraft maintenance to ensure that an aircraft is airworthy, efficient, and safe. The FAA (Federal Aviation Administration) also requires airplanes to get routinely inspected for them to be qualified to fly. A well-maintained plane delivers peak performance and suffers fewer breakdowns. Postponing or neglecting plane inspections can pose a risk to passengers. Moreover, a malfunction may lead to serious damage to an aircraft. Inspections help in discovering damaged components and worn parts before an issue arises.

Two chief types of aviation maintenance inspections are required for a Part 91 aircraft – the 100-hour inspections and the annual inspection. You are required to do only one inspection or both is determined by whether your aircraft carries passengers for hire.

Both the inspections include the same elements. The difference lies in who is authorized to carry them out and the inspection frequency.

Additionally, various equipment inspections are required besides the 100-hour and annual inspections.

Let’s have a look at the different inspections required for aircraft maintenance.

Annual Inspection

Most of the general aviation aircraft need an annual inspection. However, some airplanes are excluded that:

Possess a provisional certificate of airworthiness

Possess a current experimental certificate

Possess special flight permit; or

Use an approved plan for progressive inspection

The annual inspection must be completed as well as endorsed properly within the preceding 12 calendar months by a mechanic carrying an inspection authorization (IA). If the annual of an aircraft is endorsed on March 15, 2012, for example, the next annual for the aircraft is due prior to April 1, 2013. The aircraft, otherwise, shall require an authorization (like a ferry permit) for flying.

Ferry permit is needed for flying an aircraft that is out of annual, like when an aircraft flies to another airport to get inspected.

100-Hour Inspection

100-hour inspection is necessary for airplanes that:

Carry any person (apart from crew members) for hire; or

Are provided by an individual offering flight instruction for hire

This rule is applicable only to the individual providing the airplane, not the airplane. Hence, if the airplane is provided by a flight instructor for teaching the student, the 100-hour inspection is required. However, in case the airplane is owned by the student and the flight instructor is hired by the student to only fly with them, it’s not necessary to perform the 100-hour inspection.

The 100-hour limit can be exceeded by 10 hours, only in case the additional time is spent for flying the airplane to the site where a mechanic shall work on it. However, for example, you cannot fly for an additional 8 hours and spend the last 2 hours then for flying to the maintenance base. Moreover, you lose the extra time spent in flying to the next 100-hour inspection. Therefore, if an hour was spent in flying to the maintenance base, 99 hours remain until your next inspection.

Additional Inspections

The additional inspections required for efficient airline maintenance are as follows:


The static system of the aircraft, the automatic altitude-reporting (Mode C) system and the altimeter must have been tested and inspected in preceding 24 calendar months prior to flying IFR within controlled airspace.


The inspection of the transponder must be performed every 24 calendar months. For a transponder to be qualified for being used, its inspection must be carried out every 24 calendar months. Moreover, any modification to the transponder or the installation of one must be inspected and checked for any data errors.

Emergency Locator Transmitter (ELT)

Inspection of the installed ELT’s must be carried out within 12 calendar months following their last inspection for sufficient signal strength, operation of the crash sensor/controls, battery corrosion, and proper installation. While the ELT check is not strictly required to be completed at the time of annual inspection, it’s a convenient time for performing this inspection.

Summing Up

These are the key aircraft inspections necessary for proper aircraft maintenance. If you own an airplane, ensure that all these inspections are performed on time so that your airplane works efficiently and glitch-free.

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