AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

What Is an Aircraft Engine Overhaul

The life of an aircraft engine is not as easy as we may think, and several factors are put into consideration while determining the aircraft's serviceable life. During the internal combustion process, the metal structures inside aircraft engines undergo many heating and cooling cycles. These cycles are responsible for causing metals to degrade over time. The design of aircraft engines allows expansion to be tolerated after the operating temperature range has been achieved. To prevent major damage, aircraft engines are generally designed with the ability to expand for tolerating operating temperatures.

In the aviation world, the word "overhaul" is very commonly used in the context of engines. When discussing overhauls, it is important to understand what TBO or TBOH (Time Between Overhauls) are as they are something that the manufacturer of engines set to guide operators on when to schedule MRO operations. When these aircraft are flown at the minimum intervals, the TBO will ensure that the engine is maintained on a regular basis to guarantee reliability. While constant operation can lead to increased engine wear, those that are used less frequently than the suggested intervals will be prone to moisture collection and corrosive build-up in oil that will shorten the engine’s service life. Additionally, exposure to extreme conditions can result in increased damage to the aircraft.

What Is An Aircraft Engine Overhaul?

The term “engine overhaul” refers to a process that ensures the machine or system is in complete accordance with manufacturer specifications. Aircraft engines will be maintained and restored into a serviceable condition in this process. As some engine issues occur far beneath the outer surface of the assembly, no overhaul can be complete without a thorough inspection process. To optimally overhaul an engine, it is disassembled, inspected, and checked for defective or worn out parts. If any of these are found, they are repaired or replaced before the engine is reassembled and tested in accordance with its expected operational levels.

Types of Overhauls:

Within the aviation world, there are two primary types of overhauls, those of which are known as a major overhaul and top overhaul.

Major Overhaul:

A major overhaul involves a complete disassembling of the engine. Again, every part of the engine will be placed under inspection and repaired as required. Once inspections and repairs are finalized, the engine is reassembled, tested, approved, and returned to service within limits specified by the manufacturer's overhaul data.

Top Overhaul:

A top overhaul includes repairing parts outside the crankcase. An overhaul facility can do this without completely disassembling the engine. Generally, the top overhaul process consists of the removal and inspection of cylinders, and repairs will be carried out as necessary. It also involves the inspection and repair of cylinder walls, pistons, valve seats, valve guides, valve-operation mechanisms, as well as the replacement of pistons and piston rings. Regardless of this, some manufacturers do not recommend doing this overhaul, instead insisting on the complete overhaul of the engine when issues come about.


With a basic understanding of the process of overhauling engines, one can see why it is a very important operation to regularly conduct to maintain airworthiness during flight. If you require any aircraft parts or components to conduct an overhaul, make sure to visit us at Nascent Industrial for fulfilling all your requirements. We are a leading aviation distributor with a variety of aircraft engine overhaul parts. We are a one-stop for all your overhaul parts requirements; Get started today and see how we can serve you. 


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