Engines are like the lungs of an aircraft. Among other things, the engines are responsible for the proper propulsion of an aircraft so it can take us safely to our final destination. To make sure that they work properly, we have to make a series of tests and check the engine parameters. Tomasz Barć, Head of Production at Linetech in Katowice, which is a part of European MRO – Avia Prime, tells us how the engine run-up process works.
What is the purpose of engine testing?
– Generally, we provide the engine tests to determine if the engine is in good working order. We also check the engine parameters during the engine tests. According to Aircraft Maintenance Manual, we verify which parameters this engine should have given the ambient temperature conditions. We disqualify the engine if these parameters exceed those specified in the table, i.e. temperature, N1 revolutions, and N2 revolutions. We consider the operation as achieved when the speed of the engine is within the standards given in the table.
What if the engine tests fail?
– If the engine is disqualified it requires an overhaul. When that happens, we carry out a boroscope to determine what the problem is. Frequently, a simple engine adjustment is all that’s needed. Whenever there is an engine fault or defect, we always follow the Engine Maintenance Manual, which defines each step to be taken.
Test Cell? No, the tester is a real person
– There is no single-engine test that is widely accepted. There may be up to seven tests. These include vibration tests and engine leakage tests. Several tests are performed on race relations, which refers to the engine going up and down. There are pressure tests, which test whether the engine is providing the right pressure to the components, to the engine receivers. Aircraft Maintenance Manuals specify these requirements, and we follow manufacturer recommendations when we are performing the test.
What tools do we need for an engine run-up?
– We do not need any tools. We need a man with his knowledge and an Aircraft Maintenance Manual – the task card we need for this engine test. We use only aircraft systems that show engine parameters such as temperature, revolutions, oil pressure, fuel pressure, and so on.
Who should perform engine tests?
– People, who are responsible for engine test, should be trained on a particular engine type. We cannot perform the same tests on Airbus engines if we have been trained on Boeing engines. There are different parameters for every engine, each engine starts differently, and has different indications, so the mechanic must be trained for every type of engine. At Linetech we typically require that it has to be a mechanic who belongs to the B1 category. His training lasts about one or two days, depending on the training unit, and then he is also trained on a simulator. At the moment, we primarily test the Embrayer CF-34 engines in Katowice airport. We specialize in this field, but we also have mechanics who conduct tests on Airbus, Boeing, Classic, and NG airplane.
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At what stage of service does the aircraft undergo an engine test?
– It depends on what tasks we have to complete during the inspection. For example, we may have to run the engine after the boroscope. This is known as an engine leak check. To perform a boroscope, we must open the engine accesses, or the so-called access plugs, in order to perform the inspection. In addition to the boroscope, after closing these plugs, a leak check must be done to ensure that everything is in working order after the boroscope is performed – all plugs are closed and secured. Usually, this is done at the very end. As a result, during the inspection, during the C-check, there are various tasks to be completed on the engine. We often perform run-ups after replacing a component, as the AMM procedures specify that after a component is replaced, we should perform a check. All of this is done at the end of the inspection so we do not have to leave the hangar every time when a particular component needs to be inspected.
We collect all these tasks for the runup and then, at the end of the review we perform tests related to them.
If it rains, can we conduct the engine test?
– Engine run-up doesn’t require certain conditions. It would be more comfortable if it were no raining and the weather was a little bit warmer but there are situations when we conduct a run-up in the rain, snow, and frost and it doesn’t affect the test.
What are the risks to humans during carrying out an aircraft engine test?
– There are many risks, including the risk of exhaust gas burn. There is always a danger to drawn into the engine if the mechanic does not keep a sufficient distance. Aircraft engineer has to be careful and above all keep a safe distance from the airplane.