All You Need to Know About Aviation MROs
Aviation is a world of acronyms, and one of the most commonly thrown around is ‘MRO.’ MRO is the acronym for “maintenance, repair, & overhaul,” which is the program and acronym common to many industries.
However, in aviation, it generally refers to a maintenance facility that is certified for specific functions and capable of providing those MRO services or functions. They may belong to an air carrier (common for large air carriers) or be a private third party. The aviation industry is full of MRO facilities, some very small and niche (i.e., independent repair stations servicing specific aircraft components), to enormous MRO operations conducting depot-level repairs on wide-body jets.
Let’s dive into aviation industry maintenance concepts and MRO services to see how they work, what they are, and what they mean to you.
What Is MRO in the Airline Industry?
The airline industry is the most heavily regulated transportation industry in the world. Everything about air travel is viewed under a microscope, and perhaps few areas of airline operations than aircraft systems and maintenance operations.
Airlines bear a heavy responsibility to maintain a safe fleet, and aviation is by far the safest mode of travel because of it. To maintain this high level of safety, airlines use a variety of MRO activities to maintain aircraft operations.
In a nutshell, MRO in the airline industry is responsible for the health of the entire aircraft, although that does not mean that one facility does all of the maintenance and repairs or overhauls.
What Does Aviation MRO Stand For?
The acronym ‘MRO’ stands for “Maintenance, Repair, & Overhaul.” This concept is very common to basically all industrial markets, and the acronym means the same thing. However, we need to clarify what these terms individually mean in relation to MRO in aviation.
- Maintenance: the process of regular, scheduled upkeep (“PMs”) to keep aircraft in peak flying condition. These are regular checks and repairs, which are usually called “A,” “B,” “C,” and “D” checks.
- Repair: while it sounds the same as maintenance, it is not. Repair indicates that a part, component, or even system has failed. When aircraft components fail, then a repair is in order. Some repairs are scheduled, usually, if the OEM identifies a fleetwide deficiency, whereas breakage is found during flight or by line maintainers.
- Overhaul: overhauls are considered heavy maintenance and follow either a flight hour schedule or an isochronal schedule.
What does MRO involve?
MRO is extremely complex. The path to becoming an aircraft maintenance technician (AMT) is difficult and takes several years to accomplish.
Why? Because the extensive knowledge necessary for the job takes a long time to learn.
MROs involve:
- General maintenance
- Complex repairs
- Quality assurance
- Heavy maintenance
- Repairing structural issues
The Types of Maintenance, Repair, and Overhaul services
The acronym MRO covers a huge multitude of services. But it won't make much sense if you don’t understand the distinctions that exist. There are a few broad types of MROs and a few basic types of services they all offer. Let’s take a look at those.
Independent Repair Stations
Independent repair stations are one of the most common types of MROs out there in the wild. As the name implies, these independent providers service airlines, charter operations, and even military & government customers.
One important distinction is that the airlines do not own these (this will be important later).
Fixed-Base Operators (FBOs)
FBOs are everywhere. Every little airport in the middle of Podunk has an FBO. While FBOs generally provide fuel, mooring, and other basic services, there is usually an A&P on staff or an independent AMT that they exclusively partner with.
FBOs are not there to conduct heavy maintenance or repairs; they are generally equipped for line maintenance, although they can usually perform significant repairs and overhauls for general aviation (GA) aircraft.
However, commercial aircraft will have to use MRO facilities suited for the needs of heavier aircraft or turbine and jet aircraft.
Commercial Airline Hubs
Also known as airline maintenance departments, these are MRO services that provide maintenance to the airline that owns them. One of the best examples of this is the Tech Ops-Tulsa MRO, which is owned and operated by American Airlines. It is the largest MRO in America (some say the world), employing around 5,500 personnel and servicing approximately 900 jets per year.
Defense MRO companies
There are MROs that provide their services exclusively to the DoD. Some of this has to do with an MRO possessing expertise unique to military airframes. For example, if a defense MRO provides repair solutions for the F101-110 engine used on the B-1B, they will not have any purpose outside of defense contracts.
Some of these MROs are privately owned, although civil servants carry out depot-level repairs and maintenance
What Distinctions Exist Among Maintenance, Repair, and Overhaul?
Basically, three different types of aircraft MRO services are applied to the overall aircraft.
Component MRO
Alright, so in the basic hierarchy of aircraft composition, if something isn’t part of the powertrain (engines, gearboxes, etc.), and it isn’t part of the airframe, it is a component. The envelope of aircraft components is broad, including the entire avionics suite.
Structural MRO & Airframe MRO
The structural or airframe MRO is concerned with all things structural on the aircraft: paint and corrosion control, aero fairings, control surfaces, landing gears, all of it.
The thought process here is an interesting parallel to the FAA A&P license, which is broken into two parts: airframe and powerplant are almost always said synonymously, but they are two distinctly different certifications.
Engine MRO
The engine systems and subsystems are extensive, comprising
- Engines
- Gearboxes
- Hydraulics pumps
- Generators
- Propellors
Engine MROs are a core part of the aviation industry, as the engine systems make up a large percentage of the overall cost of a turbine or jet aircraft.
How does Aircraft MRO work?
Again, this question is a misnomer because MRO aviation companies have so many different kinds of maintenance facilities.
First, it all depends on the needs of the customer. Some MROs are small and very niche. They may specialize in hydraulic lines and fittings. Or it might be a full-service MRO that offers multiple services.
Then, there are corporate- or company-owned MROs. These service only company aircraft, but that does not mean they service everything. These MROs still outsource from time to time to specialists, depending on the severity of the issue.
It is extremely common for defense MROs and military aircraft units to outsource component repair to independent repair shops and other MRO aviation companies.
Also, it should be noted that ground support equipment repair falls under the umbrella of MRO. GSE are crucial to all commercial flight operations, so GSE MROs exist to ensure that GSE stays in peak condition.
What Sets MRO Apart from General Aircraft Maintenance?
There are not many degrees of separation between MROs and general aircraft maintenance. In fact, general maintenance is a part of the MRO concept. Preventative maintenance has higher upfront costs, but in the long run, it affords huge savings and cuts down the frequency of unplanned breakage or stoppage due to component or system failures.
An aircraft maintenance facility, particularly MROs equipped and staffed for whole-aircraft maintenance and repairs, is necessary to address all of the intricate maintenance checks that are required of all air carriers.
General aircraft maintenance does not require the heavy maintenance facilities that MROs are usually equipped with scaffolding, underwing stands, and so on It can be done (and usually is done on the line or in a maintenance hangar not fully equipped for heavy repair).
Also, MROs (speaking in this case of major airline MROs and military MROs) are built with specialized shops and personnel close at hand to facilitate heavy repairs and maintenance. General maintenance usually does not require the assistance of maintenance specialists (hydraulic systems specialists, structural and sheet metal specialists, etc.).
MRO facilities provide the logistical support needed for heavy repairs which cannot be done as part of line maintenance.
Parting Thoughts
The MRO industry is far too expansive to break down in one article, but we laid the groundwork to illustrate the most significant parts of the MRO concept. There are thousands upon thousands of MROs, from tiny mom ‘n pop shops that fix GA altimeters to mega campus MROs with thousands of employees.
All of these play a part in the overall maintenance concept for supporting operations. Behind the scenes of the MROs are the high logistical demands. When you need to procure parts for your MRO operations or specialized services, give us a call! Our proprietary GPIQ parts procurement intelligence sources parts faster and with greater accuracy than anyone else in the biz.
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