Understanding Modern-Day Aircraft Engine Overhaul Processes

The aircraft MRO landscape (Maintenance, Repair, and Overhaul) keeps changing every year due to the continual manufacture of next-generation engines. The new generation of aircraft engines is causing quite a stir in the aircraft MRO market, expanding the pressure on supply chains that were already pretty exhausted. How can engine manufacturers and aircraft engine repair experts optimize the global MRO network going forward? The top engine OEMs are dedicated to solving issues like fuel savings. The introduction of new engines is introducing new challenges to the red-hot market of aircraft engine repair.

The global aircraft fleet is set to increase by almost 50% over the next one and a half-decade. Experts expect the number of aircraft to go from 25,900 to 48,400 by the year 2039. That means the European aircraft fleet will increase by 73%, and the North American aircraft fleet will increase by 40%. The Asia Pacific fleet will witness the most significant growth, increasing by a whopping 134% by 2040.
Important legislative changes are also expected to hit the global aviation industry. Industry leaders are dedicated to creating new types of aircraft engines with higher levels of fuel efficiency. But airlines still don’t know which of their engines they need to retire, replace, or repair. That’s why the MRO market needs to be prepared to fix both legacy engines and modern engines designed with green technology features.

Let’s explore how the best Aircraft Engine Overhaul experts are preparing for these upcoming challenges.

Understanding the Process of Overhauling Aircraft Engines

All processes of overhauling aircraft engines start with one simple step – determining whether the engine needs overhauling. Operators, of course, have to comply with the recommendations regarding ideal times between overhauls (recommended time between overhauls – TBO) from the engine manufacturers. But, if an engine is in decent condition, completely overhauling it may not be necessary.

Aircraft engines with cylinders that run at least once a week and have no exhaust valve leakages don’t need to be overhauled.
Operators must ensure that the engine isn’t producing excessive metal during regular oil changes. No inconsistencies should be tolerated.
If the aircraft engine is suffering from only cylinder issues, the engine may only need a “top overhaul,” which means replacing the affected cylinders (or replacing all the cylinders).

Airlines can safely and legally reuse engines with such minor issues without requiring overhauls. So, what are the signs that an aircraft engine needs an overhaul? Some symptoms include –

Excessive amounts of metal being released from the engine’s bottom-end parts (gears, camshafts, etc.).
Engines with excessive amounts of crankcase cracks need immediate overhauling.
Engines that can’t generate expected amounts of power despite the cylinders, fuel, and ignition systems working properly need overhauls.

After determining whether the aircraft engine needs an overhaul, here’s how the repair experts execute the overhaul process.

Overhauling Aircraft Engines – The Key Steps

Here’s a brief description of what the key steps are in standard aircraft engine overhaul procedures –

Disassembly: The vigilant disassembly of each engine is the first step. Here, the engines are disassembled, and each component is taken for inspections to look for signs of hidden damage. All modules are disassembled, and all non-modular parts are kept aside.
Cleaning: Inside sealed cleaning areas, water blast machines and customized workstations are used to clean virtually all engine components. Bear in mind – this step involves complex procedures like paint stripping, degreasing, descaling, and sometimes rust elimination. So, the process water needs to be reused several times.
Testing: The overhaul technicians look for signs of damage in all engine parts using Non-Destructive Testing (NDT) techniques. Some other types of testing carried out on critical engine components include – X-ray analysis, Fluorescent Penetrant Inspection (FPI), and Magnetic Particle Inspection. These ultrasonic tests not only provide accurate readings, but they also simplify the inspection process.
Inspection: After testing, the engine components need to be assessed for reparability. These results will determine what repair processes are technically and economically viable. When major repairs are deemed necessary, the damaged engine components are shipped to private repair workshops for external processing and advanced repairs.
Repairs: Top MRO companies provide both individual repairs (for individual damaged engine parts) and complex overhauls, repairs, and modifications for severely damaged engine systems. Their repairs enhance the service life and the safety of the engines.
Assembly: All repair processes and assembled parts are re-checked and logged in the aircraft’s assembly documents. The repair experts conduct strict visual examinations to ensure all engine parts are safe and usable before the assembly. Then, the entire engine is re-assembled.
Approval: Finally, authorized engine inspection experts re-check all the overhaul steps carried out by the MRO experts. The results are compared to manufacturer requirements and the work plans of the airlines (how many times will the engine be used in the recent future?).

Despite the processes of overhauling aircraft engines becoming more complex every day, top MRO companies use the latest tools and conduct the overhauls under the severest safety regulations!